Instructions
Log into your Battle.net and the character that is the leader of a clan. Only the leader of the clan can initially create the clan channel.
Click the "Enter Channel" button at the bottom right of the screen. The panel on the left side of the screen will change to a default channel.
Click the text box near the bottom of the panel on the left side of the screen. A blinking cursor will appear.
Type "/clan (your name)" but replace "your name" with the name of your character. Press "Enter" to create the clan channel.