Fix the torn window screens
Those are standard screens easy to repair. Pull the rubber / plastic retainer material out of the groove, the old screen fabric will fall out if it did not pull out when removing the retainer. 

Get a roll of the type of screen fabric you want to use. There are different colors and materials. I like to place the frame on the floor for large ones and the kitchen table for smaller. Verify that the frame is still square by measuring corner to corner diagonally. Lay the fabric on top of the frame. They make roller tools to push in the retainer but I always cut the screen with these so I use a carpenter's pencil to push the retainer in.

If caution is used you will end up with a very nice tight fit. Use a razor knife to trim the excess on the outside edge for a good finished job.

I find the expanded poly retainer a real pain and I usually tear it during removal if you have this type of retainer you may want to pick up a roll when you get the screen it is inexpensive. Hope that helps.