how to add margins or borders??

Hello amn2892,

You can make your website blocked version simply by setting a background color or a background image.
The margins and borders on the site you specified are custom added. There is no option in the theme panel for borders and there is no way to set them globally. You have to target each element and style it using css.
As for the black border, please provide a link to the problem (to your website) so we can inspect it and find a solution.

Thank you.

Hello,
It takes a bit of custom modification to do it. You can add an extra class on the row in visual composer: http://screencast.com/t/GDM4o7r7OjlN and you can apply styles to that row in CSS.
This is an example on a block 6: http://screencast.com/t/jAT3BC8n4X
You need to target every block you place on your page and set borders to it.
If you cannot manage on your own i suggest you hire a developer to do it for you from sites like studio.envato.com because at the moment we cannot provide any custom work. (We try to help out were we can if it does not involve lots of customization)
I hope this helps
Thank you!

P.S.
About the blue spacing. That is the video container. You chose a post template that requires a video to work properly. Either add a video to your post or change the template: http://screencast.com/t/CVwGLhBQfn.
Thank you!