If you wanna join rG you need to post an application in this section of the forum.
This is the application guide if you need it: viewtopic.php?f=14&t=1399
As for your password, you should be able to change your password here: ucp.php?i=profile&mode=reg_details
. Or if that link doesn't work, click on 'User Control Panel' at the top of the page, then click on 'Profile', then click on 'Edit account settings'. You can change your password there.