Connect to FTP or if you work on local machine open this folder:
app/design/frontend/default/
And move here blank_template folder from downloaded file
Then open folder:
skin/frontend/default/
And move here blank_template folder from downloaded file
Login to Magento admin panel: www.YourSiteName.com/index.php/admin/
Mouse over on System horizontal menu, then click on Configuration.
Then click on Design, then Themes
and add to Default field your template name. Click on Save Config button.
That’s it. Have fun 🙂