In case if you wanna add a preview theme feature to your wordpress blog just like what i am doing here, you should go for “Theme Preview“.

It is a super flexible plugin for wordpress, and extremely easy to use. All what you have to do is just download it, upload it to the plugins directory of your wordpress, activate it and then start using it! .

Once it has been activated, you can start using it by typing in your browser  your-wordpress-blog/index.php?preview_theme=your-theme-name

Hope this was useful.

Peace