Cape Cod flies

Every year me and my friend head up to cape cod for a fishing trip and book a campsite in nickerson State park and every year we go there are always trout hitting flies up on the surface and none hitting live bait down lower in the water. I have a fly rod and gear, but not sure what flies to use up there on the cape. We are going to be going May 14th and staying just a few nights. Does anyone have any tips of what to use, if there is a good fly shop around Orleans or Brewster or if there are any websites people know of to find out what flies to use? Any bit of info would really be appreciatted.

I don't fly fish, but I am pretty sure there is a fly shop in Dennis, I went into it last year thinking it was a tackle shop not a fly shop

Ok thanks, by any chance do you remember what the name of that place?

Only thing I remember is it is right off 28, and is relatively close to that store Benny's. I believe this is it:

http://maps.google.com/maps?hl=en&biw=1440&bih=783&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&um=1&ie=UTF-8&q=fly+fishing+store+dennis+ma&fb=1&gl=us&hq=fly+fishing+store&hnear=0x89fb38e2ef9f7529:0xbdcb871171d71a97,Dennis,+MA&ei=xeuGT8qrKsro0QHgqoi9Bw&sa=X&oi=local_group&ct=image&ved=0CAYQtgM

There's two shown in Dennis, hope it helps.

Yeah it should, thanks when I head up Ill have to stop by and ask some questions.