i will be performing at a music camp talent show in 3 weeks and need a guitar/vocal piece to perform that would be moderately simple to learn yet able to wow the crowd...an audience favorite would be nice...anything that would make them say "WOW"

ive been playing for 6 years...mostly rock.
comin home by city and colour is a good song they would probly like i
So were talking a solo piece with just you and a guitar eh? Do You Feel Like I Do (Peter Frampton) would be absolutely dynamite if you can pull it off. Livin on a Prayer by Bon Jovi is always a big one for the audiences. But if you want simple then I'd say Wonderwall by Oasis is your best bet. Fan favourite, easy, and...well it's just awesome, although overplayed at those sorts of events. Actually...Sweet Home Alabama might be a good one...yeah...
Honestly man as long as your naked you'll likely "Wow" the crowd... Unless of course you are Asian in which case you'll likely "Aww, its so cute" the crowd...
Purple Haze is always a favorite. Just get the solo down pat, and the rest is easy.

Or were you thinking of songs with just guitar and vocals?

Was there any you had in mind?