Why the Nokia N8? The answer is simple – it is the only Nokia smartphone at the moment that works with the beta version of Belle. Just make sure that you have made a back up of all your data, and there are three things you need – Phoenix, Belle beta firmware, and Anna firmware.
Once you have downloaded Phoenix, Belle beta Firmware and Anna firmware, install Phoenix first, followed by extracting Belle beta Firmware and Anna firmware onto your desktop. The rest of the instructions can be found here, so make sure you follow them to the letter. There are, of course, problems that might surface during the process. Just in case the flashing process fails, just start from the top again since there is the possibility that you failed to press the power button long enough to have the N8 vibrate a couple of times, or your computer did not have the right driver.
Good luck!