In the "Assignments" tab, inside the group window, you will find three categories:
Active: assignments whose due date has not yet arrived or that have not been completed by all the students they were assigned to.
Upcoming: assignments whose start date has not arrived yet. These assignments are not visible to the students. Assignments saved as drafts will also be saved here. To save an assignment as a draft, you just need to click on the "x" icon in the top right corner. The assignment window will close and the assignment will be saved as it was drafted at that moment.
Completed: assignments that have passed their due date or that have been completed by all the students they were assigned to.
You can filter the assignments according to different parameters or use the "search" tool to locate an assignment by name.