In plain text, as an alternative:
Each weapon you use has a fixed damage die, which is rolled when you hit. Most melee weapons are a d8, or a d6 for example. Daggers are a d4, while great swords are 2d6.
When you deal damage, you roll the weapon's damage die, and you add to it the ability modifier you use with the weapon - the small number that's attached to each score. For most melee weapons this is your strength modifier - so if you have a strength of 16, you'll add +3 to whatever you roll with the weapon die.
If the weapon is magical and has an enhancement bonus (it will say so on the tooltip), that bonus is also added to the damage you deal.
On a critical, this video game doubles the amount you roll from the dice, but not your other modifiers. This means that if you roll a 5 on your d8 weapon die, for a critical, the game will count that as 10, then add your other modifiers to reach your final damage.
