Turnitin can be used in lieu of the regular assignment tool in Moodle. Because of it's easy-to-use grading workflow, Turnitin can be used for more than just plagiarism detection. Go to the Turnitin Assignments section to learn more.
Click to view instructor resources from Turnitin.com (white papers, web casts, etc).
Using Turnitin Assignments (video recorded on older version of Moodle, however process still applies)
You can create a regular assignment in Moodle and be sure to allow text entries (see Assignment Settings). View these instructions to learn more.