The basic mechanics for most of the game are explained in the class/skills section, since skills are the main way you interact with the world, there is also a small section back in the statistic section explaining how you can use them in a sort of brute force mechanic if you have no other way to resolve a problem.
I am just putting the finishing touches on the class skills, doing the usual sweep through to make sure none of them interact in odd ways. As opposed to the last round of play testing where a caster that wasn’t focused entirely on lobbing damage at enemies could have bulked up the melee fighters an obscene amount. It mysteriously avoided the play-testers notice so I suspect they were saving it for when it would completely ruin me.