First, Download Starcraft 2 Beta From Torrents or from your Battle.net Profiles.
Second, download Lazy Launch.
Third, download the map pack . ( Namely : Starcraft 2 Beta Login Bypass, Cache, and Replays )
Install the game and run it. It will update it to the latest patch. After that close the game and run Lazy Launch. It will take you to your explorer, choose the map you want to play and that’s it.
Keep in mind it will automatically choose a race for you and the AI. If you’re not comfortable with that, just restart the game again for your favorite race.
Here are the AI difficulty patches for StarCraft II Beta:
Very Easy
Easy
Medium
Hard
Very Hard
Insane
Original