Hi @David_Morse
Thanks for posting back the details. We are in the process of deprecating Trinity at UseGalaxy.org (technical reasons). Sorry for the confusion here … it is still in the tool panel but we are working on that part and it will be cleared up some time this week probably.
The solution is to try at a different UseGalaxy server → UseGalaxy.eu or UseGalaxy.org.au both still host it. 
These links can explain how to get an account at the others, why this is a good idea anyway, and how to move data around.