Um, how about: read the documentation which comes with it? or try it out using http://localhost:8080/ ? I don't want to seem unhelpful, but if you don't know what you want to do with it, and haven't read any of the documentation, why did you install it? If you can give us a bit more detail of what you would like to achieve using Tomcat, we'll try and give some advice more specific to your needs.
in the installation file they ask you to test if tomcat is running: like frank said:
http://localhost:8080/ if you see the tomcat welcome page you installed it correctly. Now just play with it. There are a bunch of links with examples of jsp and servlets. Run them, and check the source code.. hope it helps
I'm not going to be a Rock Star. I'm going to be a LEGEND! --Freddie Mercury