How can I find out what version of PyroCMS do I have installed on the server?
Go to your admin panel and look at the bottom as shown in screenshot --
EDIT
Check for the README.md file and look at the version --
# PyroCMS Community Edition
* [Website](http://pyrocms.com/)
* [Documentation](http://pyrocms.com/docs)
* [License](http://pyrocms.com/legal/license)
* [Forums](http://pyrocms.com/forums)
* Version: 2.0.1