It is our greatest pleasure to give you what you want. Since the very first signup, WordPress.com bloggers have wanted to edit their themes. Today is your day.
With the release of the Sandbox theme, you have a clean slate with some of the best markup ever generated by WordPress. Add to that our new Custom CSS, our first paid upgrade, and you are on your way to creating a blog like no other. You can purchase Custom CSS under the “Upgrades” link in your Dashboard.
The Sandbox theme’s skins can help you get started by providing flexible layout options; it comes with one-, two- and three-column themes with sidebars on either side. Or you can select No Stylesheet and do it all yourself.
For those who need help with their CSS and those who like to help, we have created a forum topic for CSS customization. (Podz is very talented but he can’t be expected to debug your CSS for you.) We expect there will be a growing supply of unique Sandbox stylesheets available in the wild, so be sure to show off in the forums when yours is ready!
Update: You can use Custom CSS to improve on any theme on WordPress.com. Sandbox is the most flexible theme but it’s all right if you want to just change a few things about your existing theme.