Here some explanations regarding snmp shell commands.

You have several groups. Typing "g", you will see a list of all available groups.
Typing "g <groupname>" or "g <groupnumber" you will see a list of all tables from that group.
Example:
x1200_ab:> g   <---!!!
GROUPS:
         1 administration        2 alive
         3 capi                  4 interfaces
         5 ip                    6 ipsec
         7 isdn                  8 ppp
         9 pppoe                10 qos
        11 snmp                 12 transmission
        13 vpn
x1200_ab:> g 8   <---!!!
GROUP ppp (08):
54 biboPPPTable          55 biboPPPStatTable      56 biboPPPLinkTable
57 biboPPPIpAssignTable  58 biboPPPProfileTable   59 pppLqmTable
60 pppIpInUseTable       61 pppExtIfTable         62 pppSessionTable
63 pppDialProfileTable   64 biboDialTable
x1200_ab:> g ppp   <---!!!
GROUP ppp (08):
54 biboPPPTable          55 biboPPPStatTable      56 biboPPPLinkTable
57 biboPPPIpAssignTable  58 biboPPPProfileTable   59 pppLqmTable
60 pppIpInUseTable       61 pppExtIfTable         62 pppSessionTable
63 pppDialProfileTable   64 biboDialTable
x1200_ab:>


If you want to edit a table, you have to simply type the number or the name of the table.
Example:
x1200_ab:> bibodialtable   <---!!!

inx IfIndex(*rw)             Type(-rw)                Direction(rw)
    Number(rw)               Subaddress(rw)           ClosedUserGroup(rw)
    StkMask(rw)              Screening(rw)            CallingSubaddress(rw)
    TypeOfCallingSubAdd(rw)  TypeOfCalledSubAdd(rw)   LocalNumber(rw)

x1200_ab:biboDialTable> 64   <---!!!

inx IfIndex(*rw)             Type(-rw)                Direction(rw)
    Number(rw)               Subaddress(rw)           ClosedUserGroup(rw)
    StkMask(rw)              Screening(rw)            CallingSubaddress(rw)
    TypeOfCallingSubAdd(rw)  TypeOfCalledSubAdd(rw)   LocalNumber(rw)

x1200_ab:biboDialTable>


On the SNMP shell you can create, modify and delete databases.

a.) How to create a new database: First you have to edit the table, then you have to give a value (at least) to all variables which have a * in the brackets (* means mandatory variable). You can also give a value to variables without the * in the brackets, if it is meaningful for you.
You can only give values to rw (read write) variables, not to ro (read only) variables.
Example:

x1200_ab:> ipnatpreset <---!!!

inx IfIndex(*rw)      Protocol(*-rw)    RemoteAddr(rw)    RemoteMask(rw)
    ExtAddr(rw)       ExtMask(rw)       ExtPort(*rw)      ExtPortRange(rw)
    IntAddr(rw)       IntPort(rw)       IntMask(rw)

00 0                 udp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           500               -1
    0.0.0.0           500               0.0.0.0

01 0                 esp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           -1                -1
    0.0.0.0           -1                0.0.0.0

02 0                 ah                0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           -1                -1
    0.0.0.0           -1                0.0.0.0

x1200_ab:ipNatPresetTable> ifindex=10001 protocol=udp extport=500 intport=500   <---!!!
03: ipNatPrIfIndex.10001.17.500.3( rw):        10001
03: ipNatPrProtocol.10001.17.500.3(-rw):       udp
03: ipNatPrExtPort.10001.17.500.3( rw):        500
03: ipNatPrIntPort.10001.17.500.3( rw):        500
x1200_ab:ipNatPresetTable> ipnatpreset

inx IfIndex(*rw)      Protocol(*-rw)    RemoteAddr(rw)    RemoteMask(rw)
    ExtAddr(rw)       ExtMask(rw)       ExtPort(*rw)      ExtPortRange(rw)
    IntAddr(rw)       IntPort(rw)       IntMask(rw)

00 0                 udp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           500               -1
    0.0.0.0           500               0.0.0.0

01 0                 esp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           -1                -1
    0.0.0.0           -1                0.0.0.0

02 0                 ah                0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           -1                -1
    0.0.0.0           -1                0.0.0.0

03 10001             udp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           500               -1
    0.0.0.0           500               255.255.255.255

x1200_ab:ipNatPresetTable>


b.) How to modify a database: First you edit the table, including the database you want to modify. Then you use following syntax:
<variablename>:<inx number>=<new value>
Example:

x1200_ab:> ipnatpreset   <---!!!

inx IfIndex(*rw)      Protocol(*-rw)    RemoteAddr(rw)    RemoteMask(rw)
    ExtAddr(rw)       ExtMask(rw)       ExtPort(*rw)      ExtPortRange(rw)
    IntAddr(rw)       IntPort(rw)       IntMask(rw)

00 0                 udp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           500               -1
    0.0.0.0           500               0.0.0.0

01 0                 esp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           -1                -1
    0.0.0.0           -1                0.0.0.0

02 0                 ah                0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           -1                -1
    0.0.0.0           -1                0.0.0.0

03 10001             udp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           500               -1
    0.0.0.0           500               255.255.255.255

x1200_ab:> extport:3=600   <---!!!
03: ipNatPrExtPort.10001.17.500.3( rw):       600
x1200_ab:> ipnatpreset

inx IfIndex(*rw)      Protocol(*-rw)    RemoteAddr(rw)    RemoteMask(rw)
    ExtAddr(rw)       ExtMask(rw)       ExtPort(*rw)      ExtPortRange(rw)
    IntAddr(rw)       IntPort(rw)       IntMask(rw)

00 0                 udp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           500               -1
    0.0.0.0           500               0.0.0.0

01 0                 esp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           -1                -1
    0.0.0.0           -1                0.0.0.0

02 0                 ah                0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           -1                -1
    0.0.0.0           -1                0.0.0.0

03 10001             udp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           600               -1
    0.0.0.0           500               255.255.255.255

x1200_ab:>


c.) How to delete a database: First you edit the table, including the database you want to delete. Then you use following syntax:
<variablename with the - sign in the brackets>:<inx number>=delete
Example:

x1200_ab:> ipnatpreset

inx IfIndex(*rw)      Protocol(*-rw)    RemoteAddr(rw)    RemoteMask(rw)
    ExtAddr(rw)       ExtMask(rw)       ExtPort(*rw)      ExtPortRange(rw)
    IntAddr(rw)       IntPort(rw)       IntMask(rw)

00 0                 udp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           500               -1
    0.0.0.0           500               0.0.0.0

01 0                 esp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           -1                -1
    0.0.0.0           -1                0.0.0.0

02 0                 ah                0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           -1                -1
    0.0.0.0           -1                0.0.0.0

03 10001             udp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           600               -1
    0.0.0.0           500               255.255.255.255

x1200_ab:> protocol:3=delete
03: ipNatPrProtocol.10001.17.600.3(-rw):       delete
x1200_ab:> ipnatpreset

inx IfIndex(*rw)      Protocol(*-rw)    RemoteAddr(rw)    RemoteMask(rw)
    ExtAddr(rw)       ExtMask(rw)       ExtPort(*rw)      ExtPortRange(rw)
    IntAddr(rw)       IntPort(rw)       IntMask(rw)

00 0                 udp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           500               -1
    0.0.0.0           500               0.0.0.0

01 0                 esp               0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           -1                -1
    0.0.0.0           -1                0.0.0.0

02 0                 ah                0.0.0.0           0.0.0.0
    0.0.0.0           0.0.0.0           -1                -1
    0.0.0.0           -1                0.0.0.0

x1200_ab:>


I hope it helpes!

You will find further informations and hints in the Software Reference,
chapter "The SNMP Shell" (in english!),
http://www.bintec.de/ftp/doku/swref/swref_v29/snmp.pdf.