Your setup should be similar as follows, for example:
I am using the j2ee.jar file from
J2EE, but you can set your classpath to point to tomcat's serlvet-api.jar, I believe it is called:
This will give you some idea of how your environment should be setup.
You can startup tomcat by either:
or "cd" to %catalina_home%\bin and then executing startup.bat from the command line.
If you have any questions about tomcat, I believe the good people at the tomcat forum are very helpfull.
craig.