Here is a sample way for a hatchery rush using the zerg race in StarCraft 2. The basic strategy is to rush with it right at the beginning, hatchery first, then immediately go for the Queen to lay the creep tumor. Then you start making crawlers. If against protoss or terran, make sure to get the creep tumor to spread over areas they may make cannons or bunkers. If done right, it is very easy to lift your crawlers to move them strategically to places where they will inflict maximum damage.
Here is a sample replay in 4v4 on SC2.