Over the month you undoubtedly paid for some things with cash. The entry made is exactly the same as if you paid with a check. You should have a file of receipts, and most of them will match a check (it will be easier to confirm if you form the habit of writing the check number on the receipt). Any receipts that were paid with cash should have that noted on them, along with what the item or account number was. Same entry - debit the expense account, credit the cash account.
If you have more than one cash account, have a separate account number for each bank account, and credit the account from which you are actually taking the money. If you move money from a savings to a checking account, the entry will be a credit to (decrease in) savings and a debit to (increase in) checking.
