when you use and edit something under GPL licence ? say a program or website design template , how should I write the copy rights now of the new product ?
p.s "licence are PITA I never get the sooo many terms and regulations!, i just need simple human answer please."
You don't need to do anything when you use and edit something under the GPL.
You need to take care with what you do when you redistribute your edited version (i.e. when you give it to other people).
Normally, if you are redistributing modified GPL code, the correct practice is to append your name to the list of copyright holders, since you hold copyright over the portion of the code that you wrote or modified. And, of course, the entire piece of software must continue to be licensed under the GPL. That's the most important part.
In order to keep your edited redistribution under the GPL, you must continue to include the GPL license with the software, and make the source code to your edited version available to anyone who receives a binary version of the modified software.
The GPL is really easy to follow so long as you don't try to do what it's trying to prevent you from doing, namely, taking free open-source code and making it into proprietary closed-source code.
First of all, IANAL (I am not a lawyer), and chances are nobody else here is either. As much as geeks like to pontificate on things they really know very little about, if this is a major project, consult a lawyer.
GPL comes in a few flavors. The full GPL means that if you use the code, your code needs to be GPLd too. That means people must have full access to your source code, and have the right to modify, redistribute, or resell your code.
LGPL is a little less prohibitive. It means that if you link to (i.e. use) the library, you don't have to GPL your stuff. But any modifications you make to the LGPLd code fall into the first category, you need to distribute the code to those changes, and people are allowed to do almost anything with them
If you want to know the detail of how to claim your program as GPL, see GPL-HOWTO.
Briefly speaking, you'll need to put the GPL disclaim in each of your source files (disclaim can be found in GPL-HOWTO).
You also need to download the GPL-License and include it in your software, zip, tarball..., whatever.