You can join Usergroups after you have qualified and become a TFH Graduate.
If you try joining before - you will not see the forums regardless if you are accepted or not - in order to join a usergroup you have to be a TFH Graduate.
In order to access the Join Usergroups page - you need to go to UserCP - a link is provided at the top right hand side of any page. Look for 'Miscellaneous' and second option down is 'Group Memberships' - click this link.
You will be presented with a list of joinable groups - please select which group you would like to join and click. You will be asked to provide a reason for this - please state why you would like to join this group. Your request will be sent to staff who will accept or decline your invitation.
If you are accepted - you will see the new forums at the bottom of the forums homepage. If you are declined - a member of staff will PM you to inform you why.