• If the highest die is a 6, it's a full success. Things go well. If you roll more than one 6, it's a critical success and you gain some additional advantage.
• If the highest die is a 4 or 5, that's a partial success. You do what you were trying to do, but there is a consequence.
• If the highest die is 1-3, it's a bad outcome. Things go poorly. You don't achieve your goal, and suffer a consequence.

If you ever need to roll but you have zero (or negative) dice, roll two dice and take the single lowest result. You can’t roll a critical when you have zero dice.