If you're seeing this page via a web browser, it means you've setup Tomcat successfully. Congratulations!
This server is installed from the Apache Tomcat distribution archive. Both CATALINA_HOME and CATALINA_BASE point to /opt/tomcat, and the default root application can be found at /opt/tomcat/webapps/ROOT/index.html.
Manager and host-manager applications can be deployed under /opt/tomcat/webapps/manager and /opt/tomcat/webapps/host-manager when enabled.