Is there a section on your website that isn't provided in the template? Then Add Section is the option for you 

1. Click Add Section 

2. Write a name for this section that will be read to users

3. Include a description  and all the content that needs to be in this section

4. Include a photo that will be displayed in this section (if desired) and an alt tag for the photo. An alt tag is a textual description of the photo

5. If adding multiple new sections, select the sort order of the sections and lastly click Add Section 

and with that you've added a new section to your accessible website.