Step 1: Supplies.
1. A deck of cards. (I think business cards would work.)
2. A total of two hands.
Step 2: Actually Flicking the Card
Pic 1. Hold the cards in your recessive (weaker) hand like so.
Pic 2. Move the top card into this position. Hold it there with your thumb.
Pic 3. Put your dominate (stronger) hand next to the card you moved out like this... The card should stay in your hand! I put it down because I am not a mutant 3 armed freak. I had to position my finger and take the picture.
Pic 4. Flick the card, if done right, you should have flicked it a good 15-20 feet.