The 'Site Builder' is where you will design the structure of your SocialGO site.
Every page that you add to your site will appear in the list of pages. You can click and drag these pages to place them in any order and you can also make drop downs for sub-pages. (Tutorial for that here).
Every page and sub-page can be renamed under 'Page Settings' and you can also edit the permalink of these pages. Each of these pages can be set to hidden or visible (click 'Disable Page' button, next to Page Settings to hide).
Access permissions can also be edited by ticking or unticking the boxes under 'Access Permissions' in the Page Settings:
There is also the option to delete each page or set as the homepage of your site, remember to click 'Save' after making any changes