Hi Rujina,
Could you please clarify, do you want to display Facebook chat on the website for your customers?
In this case please refer to this FB chat documentation. Basically, all you would need to do is:
- Include Facebook chat SDK Javascript onto your page (documentation). I would recommend doing it in the master template of your site.
- Setup and customize the plugin (documentation)
Or do you want to integrate with Facebook chat within your admin area? Like, post something into chat after publishing a new content?