Here is how to use the Turnitin function in Seqta, which can be used for submitting assessments and homework
Go to Seqta Learn, and under the Assessments tab, select 'upcoming'
Look for the assessment you are submitting for, it should have the turnitin symbol. If you click the button, it will take you to the turnitin page
Click on 'submit file' and click on the 'choose file' button to add your assignment
From here you can preview the file and when you are done you can upload it