rounded corners Options

[ChasingLife87]

I was wanting to try a layout (website) that would implement modules with rounded corners. I've seen it on a lot of websites as well as on the default Blogger templates [example].

I get the basic idea... like if you wanted a blue box on a green background, you would make a blue div with the content in it, and create images that have the curve with green... and then you somehow place those images in the corners so it looks like they curve. But how does the coding look? I'm not exactly sure how it works. And I really want to use this because it looks so professional