There are two quick ways to do this:
1. You may add the Cash Sales as a Journal from Bookkeeping>>Tasks>>Journals. In a Journal you would Debit the Account for "Cash in Hand" and Credit the "Sales" Account.
2. Alternatively, you may record under Sales for Bank receipts. Navigate through. Bookkeeping>>Sales>>Receipts then click on "+Receipt".
Please refer below screenshots for more help.