Do you ski?
If yes, it's pretty much like clicking out of your bindings.

If no... stay on the grass I'm sorry... someone said that to me once when I was falling all over the place.

Seriously though, do you have a trainer? If you do, put the bike on it and pedal and unclip over and over until you can 'feel' it. If you don't have a trainer ride around slowly in your neighborhood doing the same thing.

I have to re=acquant myself with my clips every season. Stick with it. Soon you'll be doing it without even thinking.