Cana nyone help

Someone gave me a factions cd key...it would acknowledge that my cdkey is valid and asks me for info.....but then when I accept it either says this key already access in your account or this access key cannot be used for this account please make another account...wtf? someone help please

sounds like whoever gave you it already made an account. so you either get their login info from them or you'll just have to bin the key as useless.