It depends how big the hole/damage is, if it's old cut outs from the socket outlets, you need some off cuts or a piece of plasterboard.
If you place a piece of timber across the hole on the internal side of the stud, you can then screw this to the plasterboard either side of the hole, to hold the timber in place, then cut a piece of plasterboard to fit the hole, screw that up.
The joints of the repair should be taped up using nylon self adhesive jointing tape.
This then can be filled out with easi-fill and sanded down after the application has dried, two/three application will be needed as the filler does shrink.
Then the area must be primed.
Easi-fill can also be used for remedial work and small damaged areas and screw holes.
There are different brands of jointing compound (I prefer easi-fill), some are ready mixed and some in powerder form (just add water)
Plus you can also buy reinforced mesh to patch with.
This will give you an idea
http://www.youtube.com/watch?v=EYQvdqcCYnI