Including a search bar in Google SERPs

How do I include a search bar into SERPs as in image below?




Thanks.

This is not a over night thing, the sites which google includes search box are enormously huge sites containing pages anywhere betweeen 20,000 to above 1 million in its website.
If you want your site to have such a authority, you certainly have to increase number of indexed page with quality content at first and after that crowd sourced content pages with low to moderate quality.

I am working on competitor of the above website, 150,000 (100,000 organic) visits a month and more than 50,000 pages website.
Above website is actually 5 times smaller, he is new player in the game, yet I have no idea how to do the same thing.

Got it http://bit.ly/1HWCk4o

I guess you can't influence on it. Google will decide it personal.