Damn, thats my biggest problem, tutorialisation :/
You basically need to use the skills on the left to move your opponents in a way so their spells (the red sqaures) hit each other when the countdown is at 0 to kill all of them.
(use mouse for all interactions and 1-5 for selecting skills, shift for next skill and Space for moving the counter down by 1. Win by killing all Enemies in each level. You can skip a room in the settings menu if it feels to hard (though all are solvable often with more than one solution)