Hi Pete,
No problem, it is very straight forward to be honest, all you have to do is plug the device into your cigarette power socket and turn your ignition on, the device lights up and shows the default FM frequency of 108.0 on its display (this can be changed if required), then tune your radio to 108.0 and save on the stereo as you would for a favourite radio station, at this point the device controls flash blue, now select your bluetooth settings on your smart phone and search, it should take only a few seconds for your phone to find the device and pair.
Your phone and the device are now connected, the device is using an FM signal to stransmit direct to your stereo. Your phone calls / music catalogue / sat nav play through your stereo, the device has a microphone built in to pick up your voice. To answer a call you just press a button on the device and speak as normal (hands free) your callers voice comes through the stereo, to call out, either use the phone built in helper (Siri for iPhone ) or select from your contacts, to cancel the call just press the device button again. One thing I have found is that you need to make sure your phones volume set at high and then regulate your stereo volume control in the usual way, this ensures you get crystal clear sound through your speakers.
appologies if my answer is a bit lengthy, but hope this helps.
just let me know if you want to know more
Cheers
Andrew