As it comes from the factory, Tomcat doesn't listen on port 80, it listens on port 8080. And yes, that is set in the server.xml file.
However, you cannot just change server.xml. On many OS's, port 80 (all ports < 4096) is a privileged port and the only applications that can use it have to have root privileges. Since Tomcat cannot jail itself, that means that a Tomcat running on port 80 is a serious security risk.
An IDE is no substitute for an Intelligent Developer.