Please carefully follow the instructions your teacher has given you. Sometimes instructors will create groups for you, in other cases you'll be directed to create your own group.
If instructed to create your own group, click on the Assignments option in the main menu. Click on the the Group Members button and add your teammates by entering their email address.
Do this one at a time for each member, and be sure each group member is saved properly. To remove a group member click on the Delete button.
If you are having trouble adding a group member because the system cannot find their email address, reach out to the group member and have them look at the email address that is saved under their User Profile within Peerceptiv.