First you need a real web server (Apache, IIS, etc). Then you need to download and modify sparkweb to point at your chat server. This is done by editing the html file and saving it as index.html. Next upload the sparkweb to your server. Provide a link on one of your pages.
There is no step by step other than what I previously told you. This software has no prerequisites, other than an XMPP server running somewhere to connect to, to install it on a web server. just download sparkweb edit the html file, upload all files.