I don't know what to do, where to start!

This post might be stupid, you might think I am dumb or something and I won't blame you for that. The issue is I wanna become a .NET Developer after graduating (I am 20 and I will enroll into University this june) but I dont know where to start? I tried making simple bank app and I succeeded but now I don't know what to do next? I don't know where to learn the proper way, I am lost.