Remove the screens from the windows. Lay the screen on a large protected surface such as a floor covered with cardboard.

Take the old spline out of the window screen by prying it out with a screwdriver. Lift the old screen out of the frame, trying to keep it in one piece.

Unroll the new screen and lay the old screen on top of it. You will need to cut the new screen about 1 inch bigger than the old screen was on all sides. To cut a new metal screen, use tin snips and wear gloves. If you are using vinyl screen, simply using a utility knife will be sufficient.

Lay the new window screen on the frame. Begin inserting the new spline in the groove using the spline roller. For this step, you will need to use the end of the spline roller that has a groove on it. Make sure you get the spline tight in the frame’s groove, while keeping the screen pulled tight. Take care not to get the screen bunched up when you turn a corner.

Trim off the excess spline when you are finished. Also, trim off the excess edges of screen using the outside of the frame as a guide. Take care not to cut the spline or the inside of the screen.