Hi and welcome to the forum! 
The best way to learn about Keyboard Maestro is to spend time on the forum.
Particularly as a beginner, if there's something you'd like to know how to do, it's a pretty safe bet that someone else wanted to do it too. Use the search function and you'll most likely find what you're looking for.
If not, ask a question. The forum is full of people who enjoy problem solving and helping others get to grips with Keyboard Maestro.
Here's a great article on how to pose a question in a way that will be most beneficial for you:
Aside from that, just dive in!