Before you can root your Nexus One phone or install new ROMs such as Cyanogen’s mod, most likely your will need to unlock your bootloader. *Unless you bought an unlocked phone straight from Google without T-mobile and whatnot, you will have a locked bootloader.
But don’t worry, unlocking your bootloader is easier than it sounds, actually it’s just a one-line command.
*Note – This will erase all your settings, it won’t touch your camera images and the SD card but it will erase all your settings so backup any data before!!!First Step – Ho