Minor Body Work

Hey all, i have a 97 golf and im not really a car person...but however i would like to atempt fixing some minor surface rust spots on my car. one spot is under the rear wiper and the other is on the rear pasenger wheel well... can anyone suggest some helpful hints or maybe some standard methods of doing this... and possibly suggest what kinda sand paper i should be using?? any help is very much appreciated!! thanks!