Your professor will supply you with a course ID and a password via email. Use this information to login at turnitin.com.
Upon navigating to Turnitin.com you will see a login area near the top of the screen. Underneath the email address field is a link that says Create Account. Click this link to continue.
Refer to the area labeled New students start here.
Click the link labeled Create a user profile.
Next navigate to the area labeled Create New Account. Choose the student link in this area.
Follow the instructions and fill in the required fields to create an account associated with your class.