To unlock the boot loader you need to have the ADT with all the packages installed and configured.
Later once the configuration is done properly then you can connect your device and enable USB Debugging under the options.
Download Modacoxe2x80x99s Superboot files and save them to your computer.
Once downloaded, extract it by right clicking and extract all.
On your phone, click on Settings > Developer Options > Turn USB Debugging On.
Plug the device in to your computer via USB cable.
Open the superboot folder that we just extracted (until you see the folder with fastboot-windows inside it), then hold the shift key down on your computer and right click any blank area.
Now, select open command window here.
In the command prompt, type the following with hitting enter at the end of each line.
adb-windows reboot bootloader (and wait for the device to reboot)
fastboot-windows oem unlock
(If it gets stuck at waiting for device here, download and install PDANet on your computer, once installed, unplug then plug the device back in and see if that fixes it)
Once it runs the device should display a screen asking you if you are sure. Click yes using the volume buttons. The device will go back to the bootloader screen but say unlocked at the bottom.