Learning to Play Starcraft
If you have succesfully installed starcraft, then you can either choose to start with the Original Campeign, or the broodwar campeign, aither one is good. But the Broodwar one is a bit more cnfusing, since there are more units and special abilities. So in order to start you off, i suggest that you start with the original campeign, because the first couple of missions actually teach you what to do and how to play.

If you are feeling lucky, and you don't really want to do the missions, i suggest that you at least get familiarised with playing the game a littel bit, and the go on battle.net, because if you don't people will call you a newb, and backstab you almost always.