Too remove the old screen, use a putty knife or a flat screwdriver to remove the old screen spline from the frame. If there is any dirt or debris in the channel, clear it out before continuing.
Make sure the screen material is at least 2-inches wider than the frame. Use a utility knife to trim the length, again leaving 2 inches excess at each end of the frame.
Pull the screen tight and tape the screen over the ends of the frame.
The screen roller has two wheels at each end: a concave wheel that has an inward groove on the edge of the wheel, and a convex wheel that has a rounded edge. With the convex wheel, roll the tool over the screen so that it is pushed into the channel of the frame.
Take the new screen spline and use the concave wheel on the screen roller to push the spline into the channel of the frame, fitting over the screen. Make sure the spline is pushed in all the way so the screen will not pop off.
Once the screen and spline are placed, trim off the excess screen material and you are set to go.