to install (flash) it on your 770 you need to turn off your 770, then plug it into your computer via the usb cable, then turn it on while holding down the home button at the same time - the screen with show the nokia login with a usb icon in the top right. Then start the nokia flasher app on your computer, it will find and connect to the 770, then select the OS you want to flash (The 2007HE file you just downloaded - make sure you got the latest one as there are 2 images out there currently) and let the flasher work its magic. Once it is done flashing OS2007HE it will reboot the device and the OS will boot up, you can no disconnect the 770 and play!