As for how to play, its kinda like punch-out.
Doing nothing is blocking, but after a bunch of hits your guard'll break and then anything gets through. You can change the keys in the option menu. For the combos see the Move lists in-game. And then there's spirit moves aka. special moves that you pull off. There's a few defensive ones as well. I think thats the gist of it...
As for a tip, playing the story mode is pretty simple, since they don't hit really hard or anything. I find evading pretty difficult half the time, so I just wait until they finish a combo, and then hit them. It works well against the AI. And if you have the spirit, you can always tuck on a special after a combo. Ippo's Liver Blow is pretty...efficient.