How to learn house construction?
I hate physics, but structural engineering is all about physics. 

The concept of “designing” structural walls, roofs, foundations, etc. is really the intersection of material’s substance and the concept of load transfer. That is to say, to design roofs, walls, etc. and their connections, you must understand materials and how they move under stress. 

For your project, I’d try to understand “common” framing methods. “Common” because they can be accomplished and “common” because they are at least cost. 

You ask if it’s different in U.S. than Europe? Yes, in fact, it’s different in Oregon than in California. Observe and learn where you are located.