Full page background image for website

1. i want to create a home page exactly like https://www.udemy.com/ with full width and full page image in the background and a black transparent box in the center with search button plus some information about the site below as in udemy. how do i achieve this in my site http://www.xprtiz.com

2. Also in my site how do i remove the pages from showing on the home page as they have to be shown when someone clicks a link for them.

3. I want to remove the black top strip from my website completely.

4. And finally want to make my theme full width / full page and remove the white space from the sides.

thanks in advance.