What is the right placement of the bagua /compass in Fen Shui?

I am trying to apply Feng Shui to my home .I am uncertain on the direction of the bagua/compass. Would it start at my door or window or what? I also would like to know since there should be no element of water in your bedroom would an air conditioner be considered.It was a built in old one.

Bagua:
http://messagenote.com/?p=37

You should stand in the center of your room or house to make the direction riht.

About bedroom decor:
http://messagenote.com/?p=5

Good luck!