Assignments in Perusall must be related to content uploaded to the Perusall Library.
1. Before creating a Perusall assignment, upload the content for the assignment to your Perusall Library.
2. In your Canvas course, select Perusall from the left navigation bar.

3. In Perusall, select Assignments from the top menu, then select +Add assignment

6. Under Content, select the content for the assignment from the dropdown menu.

6.1. You can choose to assign the entire article or a range of pages. Then, select Next step.

7. Under Options, complete the following information.
7.1. Set an assignment name, and provide any instructions for students.
7.2. Set the assignment starting date and assign to specific students if needed.
8. Choose Next step to customize assignment scoring.
8.1. Choose Use course scoring settings, or Specify custom scoring settings for this assignment.
8.2. Then, click OK to save changes.
Check this tutorial if you want to learn how to configure the course scoring criteria.