I recently accomplished the Kill the emperor at her wedding quest, and the quest after that, and all i got was a conjuration spell that lets me summons a Ghost Brother hood like the one when u go to kill Cicero, can some one tell me what i have to do or something i did that didn't give me the horse?

hes outside of the sanctuary.

You don't get Shadowmere yet. You get Shadowmere at the beginning of http://elderscrolls.wikia.com/wiki/The_Cure_For_Madness quest, which is the quest after the quest after the one you just did.

what? soo at the begining of the end quest?... and the the comment above yours, i did check outside... the horse didnt spawn