Hi Bhavin again Nice to see you there.
You have three ways:
1. To build it for free using free casino templates, but these templates are only html pages where you can add your text manually.
Such templates can be found here: http://www.gamblingtemplates.com/, but please before use them read "Terms of Use" ot these templates.

2. The second way is to buy professional templates, which can be found in Google or for example, here http://www.go4templates.com/.

3. And the third way which is the best way for all newbies is to use Joomla CMS and Joomla free templates:
Joomla CMS can be found here http://joomla.org/, download it, upload to your server and install on your server.
Free templates for Joomla can be found here http://www.joomla24.com/ http://www.joomlahacks.com/

I think, Joomla CMS is the best way to build a site and manage it. It's almost the same as Wordpress but much better, because WP is a blog, but Joomla is a real site.

For example, I use Joomla for empireofaffiliates.com.

Hope this will help you, do not hesitate to contact me.