This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
You can start off looking at the logs generated by Tomcat, they are ususally in <Tomcat Home>/logs folder. If you have Tomcat manager application installed, check if your webapp shows up in the list of apps running.