I just bought a bike and really have no idea what size i should be so im trying to figure out if this will work out. It's a klein attitude comp. size 15" frame and im 5'7. Can someone tell me if this is ok or not?

That should fit nicely, perhaps slightly on the smaller side.
I'm 5'5 and I ride a 15" Hardrock.

Posted this on your other thread as well.

How does the bike feel to you, that is what is important. Hopefully you didn't order a bike on-line without knowing wether or not it was going to fit.

Not to be a smart ass but if you already bought the bike it is kind of late to be asking opinions on fit.

I remember reading an article that suggested you have 2" of clearance on a mtb frame. That being said...listing your height alone is not really enough info to determine if a 15" frame is ok or not. What is the geometry of the bike? What is the standover height? What is your inseam lenght?
I'm 5'8" with a 32" inseam; I ride a bike with a 31" standover height.