Need help with alternator belt

[ReaperBJJ]

So yesterday when I was driving home from college I heard a horrible knock sounding noise under my hood so I pulled over right away. I looked under the hood and my alternator belt(pretty sure power steering is on the same belt, not sure though) was frayed and just sitting in the engine bay, luckily my friend was around and he was able to help me drive 16 miles back home with no alternator where I brought it in to a heated shop to work out the problem.

I got a replacement belt, but the one we looked up at the auto parts store is way too long and when I look at the routing diagram in the owners manual it says there's an idler pulley above and to the front of the driveshaft pulley. there's a little shaft in the general area that looks like a pulley MIGHT have been there but I'm not sure. and the belt on there is 6 ribbed and only ribbed on one side and the routing diagram has the belt going around that pulley in the opposite direction.

Any help as fast as possible would be appreciated as I'm trying not to miss that much of school since the semester just started this monday. So sorry for posting this here and in the tech section