Does someone know what you have to take to the store where you got your ipod to get it fix?

I got my ipod 1 year ago , & I just found out I have a warranty. & I want to know if I have to actually have to go to the apple store or I could just go to the place I bought my ipod. By the way my ipod screen is cracked & I want to know if I have to take something so they could know it has a warranty or do they just know?