westchar main quest

I did the quest to kill the wizard and hand's quest and I hear to continue the main RoT quest I need to rescue Bruenor somehow from Westchar but I have no idea where or how to start this quest? The others were pretty apparent but I have no clue where to start this one.

After you get Regis in Monzuma's Cave he mentions going to the Umar Hills. Near the Umar cave there is a drow (named Alora I think). Talk to her and she gives you the key to Bruenor's house in Westchar. This lets you enter and go the City of the Gragha and so on until you find Bruenor.

If you got the Westchar quest from the guy in front of the Copper Coronet, then you will not have the key to get into Bruenor's house. It is located SE in the town, its a big house can't miss it.

So you have to follow the main quest:
1)Chateau Irenicus
2)The slums
3)Arlax sewer
4)Monzuma's cave
5)Umar Hills
6)Westchar house
7)City of the Gragha
8)Vampire/giant area
9)Brynlaw/Spirit Soaring

I see, I briefly went to Arlax before Westchar but it seems I need to complete the quests there first, right?

Well you just have to talk to the drow in the Arlax sewer (on the left side), then Monzuma's cave, then Umar Hills to talk to the drow to get the key. You don't have to do the quests in and around Arlax or Westchar till later if you want.