It's possible to create whole new custom designs for WordPress.com blogs using the Custom Design upgrade, but making one that matches a custom look like the one at http://www.project-4.com/home.php would be an advanced design project. When you use the Custom Design upgrade, you're limited to the HTML structure in the themes available on WordPress.com. There are two which are designed specifically to be a blank slate: Toolbox and Sandbox. Take a look at those, and see if it's something that you'd like to work with.
If you'd like to control the HTML and PHP theme files, then you would need a WordPress.org setup instead of a WordPress.com one. Go to http://en.support.wordpress.com/com-vs-org/ to learn more about the differences.