WHY CANT I LINK MY DS WITH OTHER PEOPLE ACROSS THE COUNTRY!!!!!!!! PLEASE HELP!!!!!!!!!

I recieved a Nintendo DS on christmas and i cant seem to link up with anybody. On the commercials and other websites it says that you can link up and chat or play multiplayer with other people from across the room, or as far as across the country. How come when i go in the chat rooms and look for people to play games against there is no one. I KNOW IM NOT THE ONLY ONE IN THE COUNTRY WITH A DS!!!!!!!!!