Those are just places to do all of your combat math up front so you dont have to scramble around when applying them to your powers.
Most classes have about 2 'attack stats' which is what you can put in the ability place, etc.
For instance, in attack you might put +3 for proficiency, +4 for ability, +2 for magic item, for +9
While in damage you might put +2 for magic item and +4 for str and maybe like +1 for versatile weapon.
Then in the basic attacks bocks you do the whole thing, Str vs Ac 1d8+7 with the bit in your str attack panel as +to hit.
Sounds complex in type but its really, really simple.