Dear Starcraft 2 Commanders, where do you learn the closely guarded secrets of build orders and cheese openings? Well other then watching excellent match ups on YouTube, head on down to wiki.teamliquid.net for some really good information for those starting out on the multiplayer scene. Information such as these were not so easy to come by during the early days of Starcraft, but hey count yourself lucky to have such good resources to refer to now.
A word of caution though, do try to learn the Starcraft 2 lingo by reading forums and asking your friends. It does get pretty technical and you don't want to get lost when reading some critical point.
Expand fast & have fun!