If you want to create an Assignment:
- Click the Gear icon (upper right) and choose Turn Editing On
- Click Add an Activity or Resource.
- Choose Assignment and click Add.
- Give the assignment a name, description, due date, and grade information.
- Then click Save and Display.
For more information about the Assignment activity, you can read Moodle's Support documentation https://docs.moodle.org/35/en/Assignment_activity