There are two ways to create a group.  

The first is to access the slide out menu on the left by tapping the menu icon.  Next to Browse Groups, there’s a “+New” button.  Simply tap that and you will be taken to a group creation screen.  Enter in all of your data, and select done.  

You can also create a group from the Groups tab on your profile.  Simply select the + and enter your data.  If at any time you would like to modify your group, simply select the group, click on the group name and modify the desired fields.