How do I talk and IM with my friends using Google Talk?
To talk or IM with your friends for free, both you and your friend must download Google Talk and sign in with your Gmail usernames. You can send your friends an invitation to download Google Talk by clicking the “Add friend” link. If your friends don't already have Gmail, we will also include an invitation to create a Gmail account. After they download Google Talk and come online, you'll be able to talk or IM with them instantly by clicking on their name in your Friends list.