First select the joints and object then use the bind skin >>skin>>bind skin>>smooth skin, then create IK handles to make the joints move more like a human hand (otherwise you must move each joint seperately.

Then use the "paint weight" tool >>skin>>edit smooth skin>>paint skin weight tool<< or the >>window>>general editor>>component editor>>smooth skins<< so that the right joint controls the right vertexes(otherwise it will most likely just look weird.)

Best of luck!