You can create your own alliance and invite your friends to join it!
Be the strongest alliance and rule the galaxies
Creating an alliance:
If you want to make the best alliance out there...
Get at least 2 econ, select alliance in the top pane and click "Create Alliance"
Joining an alliance:
you can join one of the existing alliances...
Go to the top pane, choose ranks -> alliances, select your favorite alliance and choose join alliance.
If you know someone that already play; click the players name, select the players alliance, and choose to join it