Hi,
If you sit in your Range Rover with the engine running, press the settings icon(the one with the cogs)on your iPhone screen. Then scroll down the list to 'General', and press it. Next scroll down the screen to 'Bluetooth' and push that, at the top of the screen you'll have a little slider to 'Enable Bluetooth', make sure you slide this to the right so that it is blue. after your iPhone has searched for Bluetooth devices which takes a couple of seconds it should show something like "RangeRover H/free" or similar. Push this and it will ask you for a passcode(this will be in the audio/telecomms book in the car's document wallet. it is a 4 digit code). Enter the passcode and hit connect on the iPhone screen.
That's it job done, you'll only need to do this once, it should then connect and disconnect each time you turn the car's ignition on.
I hope this guide isn't too patronising for you.
regards steve