I'm not a pilot or cabin crew but can sympathise with your fear. A good friend of mine was also had a fear of flying and he overcame this by, firstly, doing some research on the internet into the physics of flying and what keeps the plane in the air.
Next he took a few short-haul flights to get used to flying and what everyone is doing around him.
Then he proceeded onto long-haul flights.
Whilst he still isn't the best of flyers (he takes travel sickness pills to help him sleep through most of the flight!) he is a lot better than he was.
There are also some fear of flying courses available which involve a classroom session and a flight where everything is talked through and explained.
My main advice for your flight, however, is to ask for somewhere to sit near the cabin crew and then to let them know about your fear of flying. They should be able to explain much of what happens on the flight (procedures, noises, etc) and should take extra good care of you as well!
Best of luck and I'm sure a pilot will be around soon to add their advice!