1. Start with a new file, 500×500. Then take the Rounded Rectangle Tool (U) and draw out the size you want on your contentbox and fill it with any color you want.

2. Then take the Rectangular Marquee Tool (M) and draw out the size you want to delete, done that ? good, press Delete

Now should it look like the image below.

3. Then go to the layers palette and right click, chose Blending Options and use this settings.

Then add some text to your content.

And you are done!

This is what i came up with. (Click the image for larger view)

Here you have another example with the same effects.