After your done COUNTING the cards...?

I have recently been practicing counting cards for a blackjack game. Now, I'm really good and fast with them. (of course, this has been inspired none other than the movie 21). So, I can count, but how do I apply this to the game? What do I do with my new ability to count the cards and how will this help me win the game? And this isn't for casinos, just so I can kick when playing against friends.