while adding apps to share point site, you need to configure the apps for share point server manually.
we need to follow the actions below,
http://sharepointchick.com/archive/2012/07/29/setting-up-your-app-domain-for-sharepoint-2013.aspx
http://blogs.technet.com/b/harmeetw/archive/2013/01/03/sharepoint-2013-you-receive-quot-sorry-apps-are-turned-off-if-you-know-who-runs-the-server-tell-them-to-enable-apps-quot-when-trying-to-add-apps-on-host-header-site-collection.aspx
we need to follow the actions below,
- Configure the App site collection
- Configure the App domain
- Configure an account for apps
- finally if you are having host header for that web application, you need to create a new web application.
http://sharepointchick.com/archive/2012/07/29/setting-up-your-app-domain-for-sharepoint-2013.aspx
http://blogs.technet.com/b/harmeetw/archive/2013/01/03/sharepoint-2013-you-receive-quot-sorry-apps-are-turned-off-if-you-know-who-runs-the-server-tell-them-to-enable-apps-quot-when-trying-to-add-apps-on-host-header-site-collection.aspx