dual pivot side pull brake shoe touches wheel rim. How do I fix it?
See at Sheldon's page about centering the brakes: meaning loosening the bolt that attaches the unit to the frame and rotating the caliper until both pads are at equal distance from the rim. Then re-tighten and check once more. You should also check if the wheel is correctly centered in the frame or fork. In case of doubt always refer to your LBS.