Do you have any idea. What is Digital Marketing & how can we do this?

[Jake]

I suspect that's a rather general term that might be applied to virtually any marketing involving a computer.

Here's one collection of Digital Marketing articles.
http://mashable.com/category/digital-marketing/

Motes sites are promoted by either "free" search engine traffic, which is accelerated by SEO techniques.

Here's a Search Engine Optimization primer by an SEO authority.
http://www.seomoz.org/beginners-guide-to-seo

Alternatively a site would use one of many internet marketing networks, Google;s Adwords or Facebook paid ads are 2 self serve ads systems tat may be good to start with, they work quite differently, but both have first time user vouchers for $30 to $100 floating around.