Instant messaging is useful for chatting with your coworkers and contacts without going through the phone or emails. You cannot use it to chat with people outside of the company.
Chat is by default thumbnail at the bottom right of your email screen.
Press the blue part to expand or reduce it. Your contact list will be displayed here.
To add a contact, it’s very simple! Just click on “add new buddy” and fill in his email address and his name.