The guide is intended for Windows users. I know some have gotten this to work in Linux, maybe someone can write a guide for Linux.
Why unlock your bootloader?
In order to install ClockworkMod recovery (or any other custom recovery), root, install custom ROMs or custom kernels you need an unlocked bootloader.
Warning: Unlocking the bootloader will automatically do a factory reset, wiping all your data and settings, as well as any files you have on the internal sd card....
[HowTo] Unlocking the Bootloader (Windows)
Why unlock your bootloader?
In order to install ClockworkMod recovery (or any other custom recovery), root, install custom ROMs or custom kernels you need an unlocked bootloader.
Warning: Unlocking the bootloader will automatically do a factory reset, wiping all your data and settings, as well as any files you have on the internal sd card....
[HowTo] Unlocking the Bootloader (Windows)