See the Accounts Payable topic, which describes preparation leading up to the following.

To Enter a Manually Written Check: After you have either created a new A/P record, or updated the values in an existing one, you may, but don't have to, mark it for payment (or Journal Entry). If you haven't yet started writing checks on the system, you can click on the "Manual Enter Check" button, and start that process. When you click the button, a "New Check Number" field will appear above the button, and it will be primed with the next higher check number in the system for this asset. If that's the number you want, you tab out, and another "New Check Date" field appears and displays the Current Date as set by the Calendar Form. You can change the date if you need to, but it must be in the mm/dd/yyyy format. When you are set with the date, you tab out, and a command button "Accept Check Entry" appears just below the date. Click or hit enter, and the check will be entered.

If the system checks and discovers that the number you have entered has already been used, you will be asked if you want to over-write. Yes/No, and either will be done.

Journal Entries follow the same process. However, the system uses negative numbers for numbering journal entries. You should not try to furnish a J/E number.