HOW do i enthrall the moth priest he's on one knee and it says enthrall him what do i do I've tried everything????

Use vampire's seduction and then bite him.

How can you equip it or somthing?

Yeah, it's in the magic menu under powers.

Please use the "Search" function or at least scan the first few pages. there's already close to five threads about this very subject across two sub-Forums.