I hate to be the barer of bad news, but there's a lot to cover if you wan't to make it look convincing. You said you didn't know about bump mapping so you probably don't know about UV mapping which in this case is quite crucial. You're going to have to lay out UVs to make sure your textures don't stretch and pinch.

The scratch you speak of is a seam. Think of it like trying to wrap a pic of the world map around a can of soup. You'll see where the edges meet if the info near one edge doesn't pick up exactly where the last one finished.

Edit: spelling correction :x