Download - Recovery Image Method:
Download the newest .img file here
Download the above file. Turn off your device. Turn on the device while holding volume down until the boot screen shows up. The device will now be in fastboot mode. Plug the device into your computer. If you have the right drivers installed you will be able to use fastboot. Run the following command via the command line:
fastboot flash recovery recoveryfilename.img
Note that you will need to change the last part to match the name of the file that you just downloaded. You will also need adb and fastboot for your computer.