You can find our groups gallery here where you can browse groups and join directly. http://www.palringo.com/en/gb/groups/
To access the gallery in iOS and android devices select Discover Groups, from there you can find categories of groups, popular groups or even search for groups by name. Click on any group section to enter it and look around .Once you have found a group you wish to join tap that group and tap join.
For more information on how to search for groups please see HERE