Attacking

First you must roll the die to see if you can attack the person
(example, if he has strong armour or a resistance to a form of attack in which you need to roll a 20 or something higher to attack that person)

After that you must select what attack you are going to do, then roll your levels die to see how much damage you deal, then the number from the die roll plus the number of points your attack deals is added together to get how much damage you do in total
(Example, attacking with fireball with 13 damage and you roll a 20 means you deal 33 points of damage to that persons health)