Once you have colonised some planets you will need something to do with the resources you generate.
The suggested path is to use your resources to build combat ships and soldiers. Combat ships will enable you to attack other players and defend yourself as well as your allies. Soldiers are best used for invading hostile players before they invade you.
To get started with combat you will need to build some structures. For the basic ships you will require a Colony, a Ship Yard and a Light Weapons Factory. The more advanced ships will require a Metropolis and then a Space Dock, Heavy Weapons Factory or both, depending on what you want to build. See List of Ships Page for more details.
Once you are building ships you might want to think about how to best use them. Below is a brief idea to get you started.
Combat Targeting Matrix
Fighters : These are the cheapest and weakest of any combat ship available. Their main job is to target enemy bombers but in large enough numbers can overwhelm more advanced ship types but this isn't very cost effective.
Battleships : If your enemy has these and you don't you might want to start rebuilding your ships before they crash and burn. Effective against all ship types although relatively weak against destroyers.