Where did Che Guevara learn his fight skill?

I first knew Che Guevara from the film "Motorcycle Dairy", and i have learned that Che is an important figure of Communism in Latin America. However, I don't understand one thing about his controversial life. He is a successful military leader. Even though he was both physically and mentally strong because he was once a rugby player and travelled around the Latin America, it is too unusual for this middle-cl young man to know how to organize the insurgents successfully without a military trainning, and i hope to know the detail about this part of his life. I don't care about your political perspective, but i hope that somebody can answer this question. Thank you.