that's an easy fix.
you need to go to the hardware store and buy
1. putty for drywall, sorta like white playdogh (ask, they'll know what you need. and make sure you tell them what you need it for, otherwise u'll end up buying way more than you need)
2. a putty knife (sort of an 8 inch flat piece of metal to spread the putty)
3. a sanding block w/ sand paper (DON'T just use sand paper. use a block)
4. Primer for the paint (optional)
5. Paint to match the wall. (bring in a piece of the broken part to color match the paint)
ok..
1. remove the old junk from around the whole.
2. Sand about a 1 foot circle around the hole to remove old paint.
3. Use the putty knife to apply the putty over the hole. smooth over the hole, make sure to overlap over your 1 foot circle, and be sure to put on too much putty rather than too little
4. let it dry
5. take the sanding block and sand it so it's all smooth... DO NOT SAND TOO MUCH! then you will have a hole in your wall again.
6. take the primer (basically white paint that will stick to anything) and paint a coat of paint on to the hole.. overlapping onto the old paint too. Sand this down lightly to remove any bumps.
7. paint the sucker. make sure to overlap your new paint on to your old paint, and to cover all of the primer. sand it lightly again
8. do number 7 again, but don't sand this time.
9. crack open a cold one and admire your handiwork.