Survive and kill the enemy fleet.

Pick up the green things to get resources.

1,2,3 switch weapons.

T calls in a tanker, cost 500. If you already have a tanker, T sends the tanker to the mouse position.
Tankers will get you a large bonus if you collect resources with them.

F calls in a frigate.
These are expensive, and big, and good at killing enemies.
If you already have a frigate, E or R sends the frigate to the mouse position. You can have up to 2 frigates.

Eventually, to kill enemy carriers, you’ll want to get a Missile Frigate. Press V to do this, and then V to move the missile frigate. These are expensive and weakly armored.

Make sure to defend your capital ships from enemy bombers!
Choose how much time you want to spend attacking the enemy ships vs gathering resources!
Only use your big torpedos on enemy capital ships!