The best place to learn the rules of Presidents is on the wikipedia page here.
Presidents 1.0 allows you to cusomize which rules you like to play with. There are three different rules that you can turn on or off, as you can see in the picture above. Selecting Twos Clear means that if a 2 is played, the board will clear (everyone is forced to pass), and the person who played the 2 takes control. If Suit Counts is selected, the suit of the card matters when it is played, Spades beats all, followed by Hearts, Diamonds, and Clubs in decending order. If the Run Rule is being used, a players is skipped if three or more cards are played in sequential order.
Enjoy Presidents! If you decide to keep it, you can buy a license for only two bucks. Also, check out Winner, our other great game.