The chat is a fast way to talk with mural members. You can have a conversation around your content and it will leave a running record of your conversation for as long as the mural exists.
Accessing it is simple:
Hover over the chat icon in the right corner of the screen.
Type your message, and hit 'enter' to send!
*Note: Only members and guests can use the chat function, visitors can not use or see what happens in the chat.
Everything that is discussed in the chat stays right there, so you can leave messages for members that aren't currently online.