The instant message works one of two ways (depending on how your manager has set up your account up):
To use the instant message feature, click on the "Instant Message" button on the right menu
Once clicked, the instant message window will pop up.
Depending on how your manager has set up your account, you will either see just manager usernames or both manager and other agents from the list.
If your manager has enabled you to chat with other agents, you will also have the ability to send out messages to whole groups of agents. You will see skill names from that agent list, they will be shown in brackets. For example: [Sales], [Support], [Closers]
Once you click on a user or skill, you will be able to type your message and click on the "Send to ..." button to send your message to the selected rep(s)