Write your address in the purchaser section. Include your account number if you're paying a bill.Your Signature: Your signature authenticates the money order. Step-by-Step Guide to Filling Out a Money Order. Fill in the recipient's name. 1. Buy a money order for the desired amount. 2. Fill in the "Pay to the Order Of" line. 3. 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. Most of the forms on this list will need to be downloaded in order to function fully.