From the calendar on your dashboard, go to your assignment by clicking the date it's due and selecting the assignment. You will see a dot under the date if an assignment is due that day.
You can also select Modules on the right and navigate to the assignments from there.
Once you have completed the assignment, click Submit. This may take a minute, but wait until Lingco is done loading to exit.
Once Lingco is done loading, your assignment will be submitted!