How can I repair damaged drywall?
Just buy a little tub of joint compound, or spackling and cover up the areas.  You will have to paint it as well.  If it is a hole then get a small piece of drywall slightly bigger than the hole but where you can still get it inside (you may have to cut it bigger).  Drill a hole in the middle to fit a piece of string in it.  This will help you to hold it to the wall.  Use joint compound on the edges like glue.  When it dries, fill the void with more joint compound.  I've repaired many fist-size holes from when I was a teenager.