There are many choices when it comes to creating groups and enrolling students into them.

Would you like to create just one group?  Create a single Group

Would you like Bb to create several groups at the same time?  Create a Group Set (multiple groups at one time).

Would you like to create several groups in which students can self enroll?  Create a Self-Enroll Group Set

For either of these options you can enroll student in the following ways:
1. Random - Bb assigns students to groups
2. Manual - You add students to groups
3. Self-Enroll - Students can sign up for a group of their choice.