Hi clarice,
If u have installed tomcat 4.1 then go to administrative tools-->services--> Start Tomcat from there and now try
http://localhost:8080/. And one more thing, the steps for integration of Apache web server and Tomcat Engine are given in the onjava link which u have mentions. So just follow steps from 3 to 6 for Tomcat.
If u could n't fix up the problem , write in detail what steps u followed on installation.
Good luck
[ January 17, 2003: Message edited by: Subha Ganapathy ]