Q. How can I see which students have uploaded an assignment?

Click the "Grades" tab on the left hand navigation, this will take you to the Gradebook. The Gradebook is a grid which displays all of the students in the course down the left and every assignment in the course across the top. Scroll to the right to find a particular assignment, and then scroll down to find a particular student. If you see a paper icon in the corresponding cell then the student has uploaded a document for that particular assignment. If you click in the top right corner of the cell you will open up submissions details. Submission details allows you to download the assignment as well as see when that assignment was uploaded by the student.