The best tool for helping to determine if any of your paper is plagiarized is by using the Turnitin tool to do an originality check. This is found within Waypoint, which is the same place you use for submitting your work to your instructor. Within Waypoint, select the dropdown menu and change it to "Originality Check Only" option.
If you are experiencing issues with Turnitin, review the UAGC Writing Center Troubleshooting Guide.