How to make posts roll over to the next page?

Here is my site

http://www.sportsremix.net

Whenever I add a new post, it keeps making the main page longer. I would like for the older posts to roll over to page 2.

Here is the site where I bought the theme

http://www.themeblvd.com/demo/stylez-simplistic-light/

In that example, after the seventh post, the older posts go on to page 2. Do I have to modify anything so that it rolls over like that?