if youve never used clay before then id recommend the meguairs kit or as mat said buy the clay and knock up some lube(shampoo/water)
caution should be taken when using it as its very easy to marr the paintwork and make it look worse than before you started,keep the area well lubed and dont go to heavy on the paint with the clay,just light rubbing back and forth.
as said it wont get rid of swirls/scratches