In order to join or create an Alliance, you must rebuild your Alliance Gate. Once you have reached the Iron age and completed construction you can tap the gate to learn more! 

Please keep in mind that there is a 15 minute cool-down on joining an Alliance. This means that the moment you join an alliance, you may not join another one until 15 minutes has passed.

How do I join an 'Invite only' Alliance?
To join an 'Invite Only' Alliance, simply tap on the Alliance and request to join. The Leader or Council members will then approve or reject your request.

I can't join certain Alliances!
The Alliance may been set to "Closed" or "Invite only". Additionally, the alliance may have a minimum Medal count requirement that you do not meet.

I can't find a certain Alliance
Some Alliances may be private and therefore unsearchable. Additionally, you can try unchecking the "Clean Language Only" box in the Alliance search window.