The chat automatically appears on all pages in your domain (where the giosg script is added), unless you change the settings. The chat is visible only when someone is online in the chat. If you want to limit the chat to certain pages, you need to disable the default settings first. After that you can use rules to specify where the chat is shown.
To disable the default settings go to: 1. Settings -> Domains -> speech bubble icon -> Enable. Change this from Yes to No 2. Settings -> Domains -> cogwheel icon -> Auto suggest chat to visitor. Change this from Always to Only with rules (in the Chat settings section)
After this you can create rules for showing the chat. Use the "Enable chat button" action for showing the chat button when the chat is online. If you want to send proactive autosuggest messages, use the "Send autosuggest" action. Use for example "Visitor's URL as a condition in the rule, to make a rule for a specific page.