I'm assuming you are the only one with ships you'll all be using? What do you have to use in each fleet?
A fun way to get started might be to play a simple Cruiser Clash scenario, but dividing your players into 2 teams and giving everyone control of one cruiser each. Each player in a team moves, fires etc. in the same phase, but victory points / win conditions go for the team as a whole. It might be a fun way to introduce everyone to the game, learn the rules, and get a feel for how each ship plays all at the same time.
From there, you can branch into more complex scenarios, or if you have enough ships to share, perhaps look at starting a small campaign?
Hope that helps.