Making attached images bigger when clicked

[Termure]

Hello there,

Looked for the thumbnail dimensions in hope of finding the clicked image wight/height and did not find any.

As you can see here http://diablo3.ro/showthread.php?280-Editor-imagini-gratuit the thum is ok but clicked its still small, need it at least 800x600 not 500x

Can any1 tell me how to modify that ?>

thanks