I suggest you start by breaking down what you know you need. Create small example projects that do ONLY what you want. And then start moving code into your master, or more complex, project. Along the way you’ll have questions/needs that will arise and then you can research and create more example projects.
If you’re using a database, create an example project that only deals with creating, opening, closing, and doing insert, update, delete, and with UI that allows you to list, edit, delete, etc. That will give you a rudimentary knowledge of multiple areas.
The list goes on and one but, in general, I’d say try to do things one at a time and when you don’t know how to do something (yet), create a small example project so as to not mess up your master with a lot of dumb/useless code.
I’d recommend using a source code management system (git or subversion for example) and using the Xojo Project format (not binary) and commit changes early and often for all of your projects (master and examples). That way you can back out something that doesn’t work.
Been using the product for 20+ years and many moons ago I did training for it. Try bite sized pieces rather than trying to bit the whole thing at once.