My cameras battery area is corroded! how can I replace this?

@snap2 as this is corrosion caused by the alkalinity of the battery I always use a water/vinegar mix and a cotton tip applicator to apply it. Use a toothbrush for larger, more corroded areas, like the battery compartment cover etc. In your case, I suggest that you actually dismantle the camera for a good cleaning. That way you can be assured not to get anything into the camera, which could cause other problems.

Generally to clean up corosial I use a bristle brush or qtips dipped in the highest concentration isopropyl alcohol I can find. Once done with that I would leave the camera to sit for a few hours to make sure any remaining liquid dries up and evaporates.