Go to Gateway of Tally > Accounts Info > Ledgers > Create
In the Ledger Creation screen enter the name of the GST ledger in the Name field
In the Under field, select Sundry Creditors from the List of Groups
Set Maintain balances bill-by-bill to Yes
The option, Inventory values are affected is set to No by default. Set this to Yes if applicable
Enter the Mailing Details and Tax Information
Accept the screen to save
Note: From Rel 4.8 an option to provide Bank Details is provided in the Ledger Master.
Customer ledgers can be created in a similar manner.