Hello, guys.
There's no single tutorial, but a few resources that are, indeed, scattered around. @bplus: I'm definitely considering adding a new board for the discussion to be grouped.
Anyway, here's what's there for now:
Some videos:
- Brief overview: 
- InForm workflow (although it uses the old interface it's still valid concerning the overall usage): 
- Creating a simple tic tac toe game with InForm (again, older interface, but same methods overall): 
- Extended tic tac toe game: 
- Demo of "Snap to edges" feature: 
- Demo of ToggleSwitch controls: 
- Everything introduced in Beta 6: 
- Everything introduced in Beta 7: 
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Sample programs using InForm: 
http://www.qb64.org/inform/demos/-----------------------------------------------------------------------------------------------
The project's wiki: 
https://github.com/FellippeHeitor/InForm/wikiAnd, of course, I'm always around should any questions arise.