I can't beat the mission that comes after the tutorial. Just what the hell are you supposed to do? The enemy has way more cruisers and frigates than you do, and they're of better quality. You basically get zerg-rushed by a bunch of ships that just don't die no matter how you focus on them.
In my opinion, use plasma cannons or missile launchers. They rip through sheilds easily. They also have an intense long range with them. Just order your Cruisers (or whichever ship class you use) and order them to keep moving....its should be a cakewalk. Its just a matter of trial and error.