A screen is relatively easy to replace. I replaced ours a few years ago. You will need to get a roll of screen, spline (the tubing that holds the screen in place), a spline tool and a cutter. The spline tool allows you to roll the tubing into place. Lay the frame on a flat surface. Place the screen across the frame, starting in one corner, start the spline. Use the spline roller to wedge the spline into the little groove on the frame. You will probably need to cut the spline after you finish rolling it into each of the four grooves. After you roll the spline in, just trim the screen. I am sure that if you go to Home Depot or Lowe's someone there can lead you to all the right tools and tell you how to do it. Word of warning, don't get the bug proof screen. I made the mistake of getting that for the sliding glass door and had to wait for DH to replace it for me. The screen is thicker and was harder to roll the spline into the grooves. Edited to add that if the hole isn't to big you may be able to use a screen patch on it. I would ask about that at the store.
