How do I enter a multiplayer game ?

[Ataros]

You can not create if you selected to spawn more than 1 aircraft or forgot to select aircraft or did not actually selected an airfield (double check it or try selecting a different airfield) or if the server has lag or just crashed (check in lobby if it is still up).

You can not exit multiplayer only in the May 4th beta due to a known bug. Revert to a previous version if you play online often. It will be fixed in a couple of days.