oph sorry...attack bonus...you wear armour and your dex bonus accrue to a positiv armour class, starting at a base of ten....say you had a +2 dex bonus and were wearing leather armour, granting another+2 for AC 14....all warriors get +1/level to hit, so he rolls a d20, ADDS his +1 and any other modifiers to try and hit HIGHER than the AC of 14

just all adding instead of going negative, etc.