For Sale is comprised of two sections: bidding and selling.
Bidding Each player in turn will be given the chance to 'bid' or 'pass' on a property. If you pass you are given the first card on the left for half of your current bid. If you have not placed a bid yet, you get the lowest value card for no fee. If you bid, the game continues until all players have had a chance to bid. It then goes around again and gives players the option to bid again until someone passes. The cards are then given out in order of who either passes first or has the highest bid. Strategically you could bid low just to ensure that you do not get the lowest card, however, if everyone else bids too then you may end up paying for a card you could have gotten for free.
Depending on your position and who is the first to pass, you could end up with a good card without bidding any money if others have passed before you.
How to bid on BGA: You click on the little silver coins to the value of the bid that you would like to make. You then click 'bid'.
Selling There are 30 money cards, the highest of which is $15,000 and the lowest is $0. (There are two of each -- $15,000, 14,000, 13,000, etc. -- skipping $1,000). In each round of selling, the values that appear are determined randomly. Sometimes the highest is $12,000, for example. You then select which property to 'sell' and hope that you have the highest card number than anyone else in that round. Money cards are issued based on the highest number on a card in any given round.
Properties There are 30 property cards, the highest of which is 30 and the lowest is 1. (There is one of each number.)
End of game The person who has the most money from selling + left over bidding money is the winner.