Play as either Humans or Aliens in Torn. From there, it's all about killin' and lootin' to upgrade your ship so that you can kill and loot even better.
WASD (or arrow keys) guides your ship, and left click (or space) shoots. Asteroids and enemy players provide XP to level, and provide you with money to buy new upgrades.
The arrows around your character will point you int he direction you want to go. Brown - Asteroids. Blue - Space stations.
Mine before you kill. Asteroids are a great way to build up power and earn you gold in order to level.