I recommend you start by watching my YouTube tutorial videos on how to use the engine. TODO put link here

Then check out the example projects in the QtGameEngine/examples directory. Run the examples, play with them, change them, improve them. As you are messing with the examples, read the documentation for the classes that you use (you can use the Classes link on the left sidebar or use the Search on the top right of the page) . That should get you nice and warmed up.

Next, you might want to consider looking at the diagrams in the QtGameEngine/docs/diagrams folder. They should give you a nice big picture of the game engine.