The market can be split into Antiques, Fruit & Veg, New Goods, Fashion and Second Hand Goods. For more information on where they are located go to http://www.portobellomarket.org/ - written by a true Londoner and someone who works on the stalls for many a years.
I try and trip it to Portobello at least once a month, it's a great place to style watch and if that new pair of Chloe pants are going to feature anywhere I can assure you it'll be somewhere along the streets of Nottinghill. Enjoy.