How do I fix my wall?

My wall was damaged from a leak. The paper from the drywall bubbled, so I pealed the wet paper off the wall to dry out the plaster (I didn't want it to get moldy) THe wall is all dried out now, and it hasn't leaked in several months, However a big part of plaster is exposed and looks terrible. How can I fix this? Do I need to replace the whole wall, or can I just paint over the plaster? Please help.