Add Live chat application to website

We need to add a live chat feature that allows customers to talk directly with our real estate agents. We need to feature added to the website frc-iraq.com. We want a button that allows them to open a chat box and indicates whether agents are online. We need a interface and screen name that 3-5 different people can sign on and access at the same time if needed. We also need other minor changes to the website, like insertion of new text and changing what information is displayed on properties.