The core mechanic is that you have a number of stones in the Well of Discipline and a Skill Level. Starting characters have 4 Discipline and a Skill Level of 2, so let's use that as an example. Say the Planner determines that the Difficulty is 5. So you put in a bag 1 or 2 stones of your color and three black stones, then draw one. If you draw your color, you succeed at the task and then you have 3 extra Discipline for the rest of the day. If you fail, you lose the stone(s) you risked. Note that if your Skill and Discipline were 5, then you can succeed without a test.