using this tutorial http://www.eclipse.org/birt/phoenix/deploy/viewerSetup.php#install_viewer
And it tells me to display the Tomcat manager application through this link http://localhost:8080/manager/html.
However when I click it I get an error from my browser saying it could not connect. Why is this? How exactly does one display the Tomcat Manager Application
If you are launching tomcat from within Eclipse (using the webtools tomcat server adapter) you will have to make sure you have changed the settings to use the installation directory to launch instead of the default which uses a separate location for loading and deploying webapps. So just having the manager in your webapps in the tomcat installation wont be enough to see the manager since by default tomcat launched by Eclipse doesn't look for apps in the webapps folder.
Just make sure that catalina.base and catalina.home point to the tomcat installation directory