The official site has a dowloadable client that you use to play online. There is a tutorial that will teach you the basics of the game, but I dont know of any other programs out there with a Solo playable AI.
It doesn't have the deck-building mechanic of the real game, but that only makes it easier to learn the basic rules and flow of the game. You can play against the AI or multiplayer. It also has a series of challenges which help you learn to spot the best play in any particular situation.