First clean the area with vinegar and water, this removes the dirt and grime. Second, get some sand paper and scratch up the area a bit, this is for paint adherance. Thirdly, prime the area with something like Zinzer B-I-N a primer. Fourthly, apply a good paint, one from a paint store, not home center to the surface. I would prefer a good latex, it will dry faster and be ready for use quicker.