A lot of people use this style for Neopets and stuff.

1 First, start off with the image you want to use. I'll be using the one below, so if you wanna practice with it, please do ^^ Just don't steal the background for your layout because I made it!
2 Open up the image and create a new layer.
3 Take the rectangle marquee tool [M] and create a rectangle on your image, the size you want the textarea to be!
4 Fill the selection in with white and then lower the opacity to your desire ^^
5 Add a stroke to your image. preferably 1px. [Layer, Layer style, Stroke].
6 Just add some text to it and stuff, and it will look beautiful!