My theme is currently Twenty Ten 1.1 by the WordPress team
But there is no way to make the sidebar bigger. I have 3 widgets there with text, but I want to make that bigger so it looks like 2 columsn on the webiste.
The site you link to is not a free hosted WordPress.com blog. The only themes we can use are here > Appearance > Theme. The only way to increase the width of any theme or increase the width of the sidebar in any theme that does not provide the theme option for a wider sidebar is through CSS editing, which cannot be done unless you purchase an annually renewable custom design upgrade.