Edit the quiz, click on an Add link on the right side of the page, and select + a new question.
Open the question bank and click on the Create a new question button
Select Essay and click Add
Give the question a name (this is seen by teachers only) and fill in the Question text. You will probably want to change the Default mark to a number higher than 1
Provide general question feedback
If you want students to upload a file, select Allow attachments and choose a number from the drop-down menu (Note: if students are required to write a long essay as part of a quiz, we strongly recommend they write it in Word and either upload the file or copy and paste into the response box).
You can also list specific file types (e.g. docx, pdf, etc.) if you want to restrict what types of files students can submit.