How to copy a transparent png over an existing image using GD?

Hi! I'm trying to copy a transparent (copyright) image over an existing using GD, but can't get it to work… The copyright image is a png, and can be found here: <http://adversus.no-ip.com/copyright.png>. Does anyone either know how to perform this, or knows a link to some tutorial who explains this step by step…? My problem is that the transparent image loses its transparens when I do the copyimageresized… Thankful for any help, sincerely Victor