All you need to do is crop the picture to show what you want, in roughly the correct proportions required by the forum.
In whatever software you use for photoshopping, there should be an entry to resize (typically in one of the image or view menus), where you then simply select the maximum height/width combination allowed (I think 80*80 pixels?) and then go!
Feel free to e-mail it over and I can resize it, if you want.