He was a surveyor before he got his powers. Where does he learn to fight? Because he's a fugitive from justice (technical term -- actually from injustice 0:).
I toyed with the idea of a martial arts hobby, but -- invulnerability. He's going to have to learn a new way to fight against non-invulnerable people. Especially if catching them is important. He might even have to learn a new way to fight against invulnerable.
Fortunately, I was poking about with word prompts and got an idea. He'll read some superhero autobiographies, and learn about a trainer. Who will just need some characterization to make him willing to help.
the big problem is -- when in the story does this occur? It's not like it's Star Wars where Luke can learn to be a Jedi in no more time than Leia and Han spend fleeing Darth Vader.