I realy want to build games
It’s a very good idea to start making games. You need to start with the most easier ones and proceeding to more complicated ones. It would be better to find an experienced programmer who would review your work and advise as you proceed.
Training in design is not really going to help you build games. Being able to apply a knowledge of design can help a games art, UX and UI be more polished, cohesive and usable. That’s really important, but that’s often as not polish, not the game itself.