The introductory video will begin playing as soon as you have signed up for Writers Work and logged in for the first time. Then, the video will turn into a guided walk-through of the site's features, including the Document editor, the University section, and your profile. 

If you accidentally click out of the walk-through, or if you have finished it but want to go through it again, you can access it again selecting the Guided Tour option from the user menu in the top right corner.