rawko,
Just open it up, edit it, and then click "OK". If it's a recent one, just use the "Prev" button to go back to it. If it's an old one, open up your customer list, highlight the customer, and use "Find in transactions".
NOTE: If you are editing anything that affects the dollar amount, and you have already made a deposit that includes the sale, you will need to delete the sale from the deposit first.
Russ, NCNE