Hi Gordon
had a quick look on THE list
http://www.accordionlinks.com/manufacturer.html - it looks like Rivoli was both the name of a Sonola model, and an American accordion manufacturer. Sonola is Italian, one of the well-known ones; Rivoli isn't.

If it's old & musty then it may well be out of tune, or leaking air which will make it unattractive to play.
There are loads of instruction videos on YouTube which will take you through the beginning steps of playing accordion. I found them too slow & boring, and preferred using teach-yourself books. Karen Tweed has just published a new one, which is probably excellent (haven't bought it as I'm past that Abs Beg stage now).
http://www.karentweed.com/CDs.htm for details of the tutorial book & CD deal.
The accordion is an amazing instrument, capable of a huge range of expression & passion in the right hands. Unfortunately, it has also been used to perpetrate crimes masquerading as music...
For examples of great, passionate, expressive playing, check out music by Karen Tweed, Groanbox, LAU or Maria Kalaniemi.