如何从main中的函数读入2d数组

Alright so I'm sure this is pretty simple and all but I have no idea how to use functions. Up until now I was able to get by with everything in main but now I'm required to use functions for just about anything I do. So from my code below, how do I read in (or w.e. the proper terminology is) a function from main?Alright so I'm sure this is pretty simple and a