Where would I look for a good website to learn about and then sell a vintage motorcycle?

There are a million sites out there, here is just one

Haul it to Daytona, Sturgis or other biker rally. If you can’t find someone at one of those that is interested in it, it isn’t worth the effort of fixing.

A 1972 Yankee is not a “vintage” bike. It is either usable or junk. There is no enthusiastic fan club for them – they were never regarded as a high end bike even when new.

Thank you all very much. I have a lot to learn.

Yankee Mags
The Motorbike Archives
These are just two I found by typing 1972 Yankee Trail Bike in my Goodsearch search box. Every search results in a donation to my favorite charity.