Q: and how/can you save it on yoru computer?
A: I'm assuming that you have a 'flatbed' scanner, that it functions correctly, and you can activate it. First, carefully clean the photo to remove any dust, fingerprints, smudges, etc. Otherwise, they WILL show up in the scanned image, and if they do you will have to Photoshop them out. My experience in scanning photos is that you need to set your scanner resolution at least 300 DPI, 600 DPI if you can. Bear in mind that the higher the resolution, the bigger the file and the more time it takes to complete the scan. If your scanner has some scanning options, check them out. Particularly, the Descreen option. Set your scan to 16.7 million colors. Most scanning software will ask you 'where' you want to scan the picture to during the scan process. If you have Photoshop, send it there. Lastly, if you have Photoshop, use it post scan to enhance the image and save it in the format that you want, usually Jpeg.