adobe photoshop - How to make a image fade out to both sides

I want to use an image in different screen resolutions with fading and the same background color. In a website, the image will not scale, but the background will. Something like this:

Answer

You can do this by using a transparent gradient mask.

This tutorial is quite similar, just use your background color in a separate layer underneath: http://www.mediacollege.com/adobe/photoshop/transparent/gradient.html

More details on masks: http://www.creativemac.com/2003/07_jul/tutorials/psgradient030723.htm and http://wegraphics.net/blog/tutorials/photoshop/photoshop-for-beginners-understanding-layer-mask/