the FAQ's are at the bottom of every page: https://datingnmore.com/site/faq they have a lot of answers about how to get things done. If its not in the FAQ, then chances are its in the help forum.
with this new software it depends on the device you are using (desktop PC laptop, tablet, or phone) exactly what the pages look like. so this is a general description. At or near the top there is the word Groups (it may be hidden under a menu, too), click it. then if you find one that may interest you click it. If you like what you see inside the group there should be a join button for you to click, however some groups are private and you need an invitation. See the creator (Admin) of the group to get the invite if it is a private group.
hope that helps some.