[pushkins]

lean out any loose drywall left in and around the hole, including any torn paper, cut a piece of drywall about 2 inches bigger then the hole, now turn the cut piece over and carefully cut the back paper and some way into the chalk the same size as the hole being really careful not to cut through to the face paper, also make sure that you have about an inch excess all the way around . When you have all sides cut, bend the drywall one side at a time and peel the drywall and "back" paper from the face paper (white side), repeat this for all sides. When you are finished you should have a face paper side (white) that is about an inch bigger all the way around than your hole and the reverse side should be about the same size as your hole.
Now put drywall compound in the hole on the broken edges and on the wall around the hole, also add some compound to the piece to be fitted in.
Press the piece into the hole and with a trowel/spatula press out the edges of the patch to remove any excess compound. Let it dry (12 hours) then cover the entire area with a coat of compound, you might have to do a couple of coats to get it nicely feathered out.
Sand, prime and paint.

You can if it's easier get a hole patch kit from a hardware store but seldom do they successfully hide the patch, they pretty much cover the hole.