Open Flint and click "+ Add"
Click "Create in workspace"
Adjust your group's name, description, and default tutor.
The name and description will be used to make the default tutor, which is available to students 24/7 to answer questions related to the group.
Click "Create"
Once created, you'll be brought to the page of the group you've just made.
Share the group
See here for more information on sharing groups in Flint.