Okay, so I decided to play through the Dawnguard side even though Lord Harkon side is recommended, and before I am able to enter the Soul Cairn, Serana gave me the option for her to trap some of my soul in a soul gem or turn into a vampire. I chose vampire. Is this any different from when Lord Harkon turns you into a vampire? Because I am trying to figure out how to fill up the skill bar for Vampire Lord and it says I need to use drain life or the bite power attack and I have no idea how to use that as a vampire. Any help would be nice! No stupid answers either.

It is different in the fact that you can't complete Radiant Quests for the Volkihar to gain items that empower your Vampire Lord Form. If you become a Vampire late in the storyline as a Dawnguard, you don't get access to the Amulet of Bats, the Amulet of Gargoyles, the Ring of the Beast, the Ring of the Erudite, or the Bloodstone Chalice.

You level up your Vampire Lord perk tree by killing living (or vampire) enemies with either your Drain Life spell (right hand) or your bite power attack (opponent has to be low health when you power attack in melee mode). You have to be in Vampire Lord Form to level up it's perk tree.

Okay cool. Thanks for the help I'm just going to look up what those are an see how fast i end up regretting going Dawnguard.