Okay, no problem So go to that link EER gave you ( http://forums.getpaint.net/index.php?showtopic=6305 ) and download the .zip file. Then open it and you will see a file called "OptiPngFileType." Keep that window up, and now find paint.NET by pressing the windows key and typing c:/program files/paint.net and pressing enter. You should see a ton of weird stuff, but just double-click on the FileTypes folder. It should be empty. Then go back to the OptiPNG plugin.zip file and click on the file called OptiPngFileType. Then press Ctrl+X (or right click it and select cut). Then go back to your FileTypes folder and press Ctrl+V (or right click and select paste). Now open paint.NET, and when you save an image, you should see an option called "OptiPNG" in the drop-down menu. Yay, it worked!