Measure the area on the gate where you plan to attach the screen mesh. Cut a piece of screen mesh to the specific size using a sharp utility knife.
Remove the gate from the fence and lay it on a flat surface. Position the screen mesh on the gate in the location where you want it to go.
Staple the screen mesh to the gate using a staple gun and rust-proof staples. Start in one of the corners, moving on to the other three. Continue to staple around the perimeter of the screen mesh into the gate below until firmly attached.
Place the gate back into its location on the fence to complete the job.