How do you apply skada damge meter to your World of Warcraft account

Download the addon. You can usually find this on the Curse Addons website (listed in the links). Save it. Then move it to your addon folder in your World of Warcraft folder. To find the folder go to your wow folder, then interface, and inside that should be addons. Next time you are at the character screen an addon button will be on the lower left.