Now that I understand you only have access to a course, we can make progress in making your groups. Referring to your previous picture, click on Groups.
On the new page you have a number of options on how to create and populate the groups.
- If you don't care about the group name and who is in each group, you can let Moodle handle it by clicking on, Auto-create groups, and set things on the it's following page.
- You can manually do things by clicking on, Create group, select a group name you create, then Add/remove users.
- You can use a csv file to, Import group names...directions here: https://docs.moodle.org/31/en/Import_groups
Don't be afraid to experiment as you can delete one or more groups and try again until you get the results you want without it deleting any students.