Your profile will be visible on the top right corner of your screen. You can either set your status as Active or Away. The incoming chats, as well as the chat queue, will be visible only if your status has been set as Active.
When a chat is initiated by a visitor, the Waiting ticker lights up, along with the name of the person. You can accept the chat by clicking on the green tick mark against the name.
If there is more than one person in the queue, clicking on Waiting will expand the list of people who are waiting for a response. You can choose to accept any chat from the queue.