Do I need to create a new account though I already have the old account to check turnitin.
For your information, if you already have Turnitin Account, you do not have to create a new one for new paper submission. Just use the old account, and what you have to do is just enroll in a new class. Notify the 'Enroll in a Class' tab above the 'Home' page. You may require to fill the Class ID and Class Enrollment Password that you can get from your current Instructor.