Once you have Openshift account open just click on Add Application...
Just type "ghost" in search box and choose Ghost with MySQL on OpenShift
Now just fill out missing info and click on "Create Application"
That is it! You now have running Ghost blog.
Click on your application to view your blog url.
When you open the url you can see your blog. Now sign up to your Ghost blog to access your admin console by opening this url <your blog url/ghost/>. Again reload the url to sign in to your blog .