How do I check caulking where roof meets sidewalls?????

There probably isn't caulk on the sides...the roof material is probably wrapped over the edges and secured under some kind of molding.

Check the front and end caps. That's where there is probably some Dicor type caulking...Eternabond is the absolute best way to go...around the entire perimeter of the roof... it is a big job but certainly do-able.