Closing stock values have to be specified when accounts and inventory are not integrated. Tally allows you to specify closing stock values even if your books are integrated. It would simply ignore the specified figure so long as you maintain the integration. If and when you select to separate the books, the specified values would automatically be considered.
To enter the closing stock as on a specific date, you must alter the ledger account. Simply follow the ledger alteration procedure or go from the Balance Sheet via Current Assets.
Go to Gateway of Tally> Balance Sheet> Current Assets> Group Summary
(or)
Go to Gateway of Tally>Account Info.> Ledgers> Alter (Single)
Assuming that you had a ledger account 'Stock ' under the group Stock-in-hand the information would be as follows
You are allowed to alter the opening balance as well as specify/alter closing balances on different dates. You would typically specify Balance Sheet dates so that the Balance Sheet reflects the amount of that date.