Simple? Copy and Paste Button Help

I have spent the last hour trawling Google trying to find out how I create a Copy button. So far I haven'y managed to find anything that works or that I understand..

Basically what I am doing is having code in a textarea that I need the user to be able to save. I cannot use right click as it's been blocked on my theme.

The alternative is to create a button that the user presses and in doing so it copies the code which he can then paste into his site.

Thanks.

EDIT** It must work with IE and FIREFOX

 

Google it. W3C have a load of tutorials on it.

 

I already did. Didn't find anything though

 

Maybe im not searching for the right thing?

 

search for copy button with javascript or ajax.