I had setup chart of accounts, customer,vendor,item posting groups for my client now wat is my doubt is how to set up initial amount for the bank account my client is implementing navision this year so how to enter the amount in bank column
It depends what the client wants.
The opening ledger balances would be a geneneral journal, if you want the detail behind the figure then you post this as a separate journal with the details, for example opening vendor or ledger transactions. The same is true of the bank, it is just a general journal to the bank, the offset account can be an opening balances account where the opening TB journal also points to this to net the bank to 0 and have the details make up the opening balance.
What I can pick out from the above statement is that you are left with making the opening balance for your bank account. On another look it seems you have created the main account and you need to make the sub-ledger entries. If you are left with the bank account only the above suggestion by Adam is perfect. If you however have all the balances pending you may need to set up a posting group for each category (e.g. Vendor, customer e.t.c.) that will direct the entries to the opening balance account as suggested above by Adam.
And for inventory you need to use inventory Journal.