Valid for Moodle 2.8. Updated on7/20/2015. Moodle does not have a dropbox feature, but the same functionality can be achieved using the assignment activity. To create this activity, go to the Add an activity... pull down menu and select Assignments. This will bring up the assignment setup interface. The interface is divided into several sections.
Enter a name and description for the assignment. The description would normally be a brief description of the assignment. In this situation additional files are unlikely.
In the Availability section the Allow submissions from and Due date values determine when the assignment will accept submissions. The default is to make the assignment available the day it is created and have it due in one week. The Cut-off date allows your students to submit files even after the due day.
The Submission types section should be set for File submissions. You can then set the number of files the students can submit and the maximum size of any submission.
The Feedback types section controls the feedback you can give the students. If you want to return files to the student be sure to check the Feedback files checkbox. If the student submits a .pdf file, you can edit that file directly in Moodle and the student will be able to see the editing.
In the grade section use the pull down menu to select the number of points associated with the assignment, or No grade if the assignment is not to be graded. Select the category if you are using categories in your gradebook.
Remember to click on either the Save and return to course or Save and display button when done.
See the help page on the assignment activity for details on the other options during assignment creation and for information on how to access and respond to submissions.