You need the screening material, give an additional few inches weather it’s aluminum screen or vynial, next find the spline it job is to lock the screen materials in to the groves of the frame. You will want a dull kitchen knife to remove the old spline. There is a spline tool that resembles a plastic pizza cutter, it job is the push the new spline into the screen channels. The harder part is keeping even tension on the screen. I started in the middle securing the frame, took it to the middle bottom. And started pushing the spline in.
Here's a step by step:
Also local hardware store(not big box) will often do this pretty inexpensively. Just take it to them for a price.
After my husband tried to replace torn window screens ( it wasn't tight enough ) I took them to my hometown's hardware store and had them repair them properly. Sometimes a professional is called for ;)