To enable Proactive Chat you must embed the chat application within a web site. Embedding the chat application within a web site is just a matter of adding one reference to a JavaScript file.
The URL to the file is available in the Chat Queue Settings page in the administration portal. It is listed as Proactive Chat URL. Simply copy the URL and ask your webmaster to include a script reference to it within the desired page(s) in your web site.
The URL to chat should look more or less like this:
"https://manage.mycontactcenter.net/webchatscripts/<your account ID>/<some random ID>/webchat.js"
The script reference to be added within your pages should look like this:
<script type="text/javascript" src="https://manage.mycontactcenter.net/webchatscripts/<your account ID>/<some random ID>/webchat.js></script>
The script file is automatically updated when changes are made to the chat queue settings.