From your Shopify admin, go to Online Store > Pages.
Click the Add page button to create a new page.
Enter the title of the page( such as "FAQ"), and choose the template is "page.faq".
Then click the Save button to save the page.
From your Shopify admin, go to Online Store > Themes.
Find the theme that you want to edit and click Customize.
From the top-bar drop-down menu, select FAQ ( this is the title page which you created in part #1 ).
Click the FAQ section on the left.
Full width: turn on/off displaying the section in the wider layout(still keep the gutter on the left and right).
Hide on mobile: not show the section on the mobile screen.
Scroll up to the top, you will see an Add item button, click this button to add a new item. Or you can click one of the available items to edit/remove it and drag/drop items to rearrange them.
Title: enter the item's title.
Content: enter the item's content.