How can I fix chipped paint from the wall?
You'll want to fill and level the patch with some spackle or joint compound (drywall mud). Carefully remove any loose paint first. Use a putty knife to press and level the material. Sand lightly when it's dry.

Then repaint, ideally with a small roller to create a similarly-stippled texture. Blend outward to better hide the new paint. 

If you don't have paint on hand from the original job, you'll probably need to paint the entire wall, though you may not need to completely edge everything if you get a close match.