http://www.webreference.com/js/tutorial1/opener.html - you can find everything on this page. but if you will have problems even after reading this just give some more details and I will help you out with the scripting
BDS

I found this solution:
Im openin a with a pop-up my crop.php
and then use this button to copy values to main window

pic is a input box <input name="article_pic" type="text" id="article_pic" />

value1 is the new value i want to copy from this window!
Click, Copy & Close

OK now I need a little help.

I want to add content to a <textarea>

tried with: document.getElementById('text').value='SOMETHING';
but didn't work

[edit] getElementById('text').innerHTML=''; Works, but if I edit the inserted text, or delet it, then it doesn't work anymore

I nned to check If textarea has something written in it, then just add it to the end of textarea, not replace the whole content! ELSE, just add it

Thanks!