Write your address in the purchaser section. Include your account number if you're paying a bill.1. Buy a money order for the desired amount. 2. Fill in the "Pay to the Order Of" line. 3. Underneath the "Pay to the Order Of" line, you'll find the "Purchaser, Signer for Drawer" line. Write your signature on that line. It's similar to signing a check. You'll see a line for the purchaser's signature, usually on the front of the money order near the bottom. To fill out the money order, you will need to "Pay to" U.S. Department of Homeland Security. Fill in the recipient's name.