1. Right click one of the people's names who you would like to start a chat room with, and choose "Invite to Chat..."
2. A window will appear that looks just like a normal chat window. When it comes up, go up to the menu at the top of the screen and click on "View", and choose "Show Chat Participants". Another window will extend from the chat window.
3. On the bottom corner of that window, there will be a + button. Click on it, and it will allow you to invite more people to the chat.