Press 's' or click on skills at the bottom right of the screen. Then go to 'shaman' tab (i think) and click on skill level up. If there aren't any there, press 'c' and go to 'skill' tab. Double click the card there to learn the skill then do step 1. If there's no card there, go to your trainer and buy a skill card. Then do step 2, then step 1.