Replacing my torn window screens myself is easy if I have the right tool. A Spline Roller Tool looks like a miniature pizza cutter. And a spline looks like a long, gray or black string of rubber spaghetti. The spline is what holds your screen in place in the frame, but it's very hard to shove the spline and new screen material down into that little 1/8" frame groove without a Spline Roller Tool. And you don't want to use your sharp kitchen pizza cutter for this because it will cut through the soft rubber spline and new screen material.
The Spline Roller Tool has a single edged, convex rotary blade on one end for setting the screen into the groove, and a double edged, concave rotary blade on the other end to seat the spline into the screen in the groove. I like to use a flat-bladed screwdriver to tap down corners, but you want to be a little gentle around the corners so as not to rip the screen on the sharper point there. The wooden hand grip of the Spline Roller Tool is smooth and comfortable to hold, and you'll need to use some firm pressure to seat the spline.
According to the store product description, the Spline Roller Tool from Lowe's comes with instructions for use, but they're not very informative instructions if you've never replaced a screen before. I learned how to use a Spline Roller Tool from my local True Value hardware man, who walked me step-by-step through what I would need to do to make my own custom-sized, removable window screens for every window in my mobile home. But because I couldn't find a Spline Roller Tool on the True Value website that doesn't sell their products on-line anyway, then I would recommend that people go to Lowe's to find out more about this handy screen repair tool.