Take it back to the body shop. BUT if you aren't comfortable doing that, get a pc (yep, more money) and use 3M Perfect-It II fine rubbing compound on a polishing pad. Follow this with Meguiar's DACP #83 on another polishing pad and finally Meguiar's Swirl Free Polish # 82 on still another polishing pad. Don't apply wax or sealant for at least 3 months if it is new paint.
This is the process I ended up using to take care of a body shop swirling problem on my black Hemi.