Go to your PM inbox (or user account control panel), and look on the left hand side. Scroll down towards the bottom and click on "group memberships." A whole bunch of options will be displayed - select the druid "join group" thingy, then scroll down and click the "join groups" button. You will be asked for a reason you are requesting access - just put your character's name.
Wait for someone to wander by and approve you for access.
