Shoi explained it well. You become an officer in someone else's fleet, that's the basic idea. Then as you participate in battles, you will gradually get promoted (which might mean a better ship, an escort, different layout options, higher pay, etc). None of it (aside from your pay) will belong to you however, it's being loaned to you by your faction/ commander for as long as you stay a member of their fleet. The compromise is that you don't have to worry about fleet management or supply and fuel costs, you can just focus on your own combat capabilities. Once you reach high enough reputation, they might let you keep your ship and start your own fleet.