Click on arrows to select a bar code. Then click on the Scanner.
It DOES work with the camera, however it is a bit tricky. You need the right lighting (for good contrast) and the barcode has to be big enough, so you dont have to get too close to the camera (which makes the barcode blurry). I had succes with scanning barcodes from the display of my smartphone. Also make sure, that the codes are valid UPC or EAN-13. Google for "barcode upc" or "barcode ean-13".