metroeloise, I get the feeling you're still unsure of the integration of Lighroom and Photoshop CS4. One key is to open the file as a Smart Object in Photoshop or open it as a Virtual copy.
You can view this Adobe video to get a better understanding of how to work files between Lightroom and Photoshop.
http://tv.adobe.com/#vi+f1584v1019
Hope this helps you get a better grasp of things.