How does the wireless thing work with Pokemon Firered?

I dont have the instruction book im afraid, so i cant get it figured out. And what does it allow you to do, when you have it up and running? Is there somewhere in the game you have to be to be able to use the wireless thing?How does the wireless thing work with Pokemon Firered?
The wireless adapter allows you to play games on ';two island'; and recieve mystery gifts. You may also chat, battle, and trade in the union room via adapter.How does the wireless thing work with Pokemon Firered?
Their is a systerm called GTS for nintendo ds only an it allows you to battle anyone around the world and you can also trade pokemon and also some special pokemon will evolve through trading like haunter to gengar/graveler to golem/machoke to machamp.