The demo theme has some special pages like Landing page , Static pages (Privacy, Terms,...) . How to configure it as good as the demo site?

1) Landing page : http://themes.simplifysocialnetwork.com/ 

2) Privacy http://themes.simplifysocialnetwork.com/index.php/... 

3) Terms http://themes.simplifysocialnetwork.com/index.php/... 

This article guides to set up those pages as good as the demo site.

1) Set up landing page

Set up blocks User Sign Up & Welcome at position Block 3 and Block2 respectively

Edit content of Welcome block in the theme's customization space

HTML Content for Welcome block. Download here 

2) Edit Static pages (Privacy, Terms,...)

Login the site as admin

Go to a static page & press on the bottom right corner

Download and past this HTML content into. Download here

You will have the page as above.

This a a basic setting, you can edit it as you want.

Remember that each theme has its HTML structure. If you want to customize it, it's quite possible but you should know to style it as you want.