How to run a drupal application in github?
You can not execute Drupal in Github, just because Drupal requires a server running PHP, which isn't supported by github.


  Github Pages is not a full-featured web host. It will not execute PHP, or any other arbitrary code.
  Source


You could convert your Drupal site into a static site and upload it on github, but the website would not be dynamic anymore. If you decide to do this, you could host it using Github pages, but you would not be executing Drupal; instead, you would be going to show a static version of your Drupal website.

If you wish to add a static version of your website for Drupal 7, you can look at the Static Generator module. If you are running Drupal 8, you can use wget --mirror http://example.com and this will provide copy of your site's HTML.