Making a Shroud

Well thank you for not making feel like an idiot. I looked online and could not clearly find an answer. One more question Is it possible to roll a circle without a roller? If so any suggestions on how would be awesome. Ohh and reason to not pop rivet the corners?

No reason at all that you can't use pop rivets.
Just be sure none on the ends of them are rubbing the radiator anywhere.
You can use that sticky foam insulation strip stuff between them for sealing.
As far a rolling a strip of steel, it might be worth having it done by a shop with a roller.
I'd be tempted to do it by hand, but not really sure how to make it nice and evenly rounded.