Participation in an Obsidian Portal campaign allows you to create a character, contribute to the wiki and adventure log, and add to the overall narrative of the story. To do this, you must be one of the campaign's players, which means you'll need to be invited by the GM. This invitation will appear as a notification on the messages icon on your main navigation when logged in (similar to how a private message does; see View a New Private Message). A link to accept the invite will also be sent to your account's email address.
To join a campaign:
Click the message icon on the top bar navigation.
Locate the "CAMPAIGN INVITE" inbox item.
Click the "Accept" button.
Click "Okay" in the confirmation dialog box.
After confirming that you wish to join the campaign, you will be added to the player roster, and will have the campaign added to your campaigns listing on your profile page. You will remain a player in this campaign indefinitely unless the campaigns GM removes you as a player, or you choose to leave the campaign (see Leaving a Campaign).
Note: The acceptance link sent to your account's email address will automatically add you as a player of the campaign, and negates the need to Accept and then confirm in the dialog box.