First of all, choose a screen type. If only a tiny part of the screen is damaged, make sure you don’t buy a different style. Available in various colours and shades, Vinyl cloth or fibreglass are one of the long-lasting screens.
Aluminium screens and solar fibreglass are also good options. It entirely depends on your choice though. You may find a few screens very expensive.
It is always better to buy a little extra screen than your required size. After getting the new one, you must cut the replacement material to the size. Lay the entire material on a flat surface, and gently cut it. Make sure the edges are not sharp.
After preparing the new material, it is time to remove the old one. Use a nail-punch or other sharp object to open the plastic spline that is holding the old screen in the frame.
After getting the spline loosened, gently remove the old screen. You must wash the frame before going ahead. Use a damp cloth to remove the dust, if needed.
Now lay the new screen across the frame. Slightly bend the screen in order to insert it in the frame. After confirming the proper placement, put the spline back.
In order to get more durability, you can replace the spline. But if it is in good state, this step is not recommended. Spline is not an expensive product, and you would easily find it at any home centre. Use a sharp knife in order to insert the concerns of the screen in the frame.