You simply talk to them on their profiles. There was so much spam on Chat that they deleted it. Talking on profiles gets you AP and you can even leave messages about if you're leaving, when you're coming back, or your friends can leave you a message when you're not online so when you get back you can read it!
No no no Armor Gamers. Chat has been taken to your uncle's farm out in the country, where it will have room to run and play. It is a better life for it.