REALLY!?! You need a tutorial on how to shoot the promo girls? Fine :)
First things first. The promo girls only come out to play on Stadium Court. You are guaranteed to get them during the men's and women's finals, and possibly also the semi's.
The girls who throw schwag into the crowd will typically position themselves equi-distant between the net and end-line, or midway along the endline. Dancers will usually arrange themselves in one or both of the serve receive areas.
In terms of positioning, I would suggest that you be down in the paid seating area, preferable in the first 5 rows, that way you aren't shooting down at them at too great an angle.
For camera settings I shoot as close as my lens can get and as wide open as possible (which is typically 150-200mm@F2.8 on a 1.5x crop camera)
Happy Hunting!