it means you don't have compelete set of jar's in classpath for you to run that command.
If you are using eclipse it will help you to solve this problem very easily, just create a Dynamic web project and copy your WSDL in to that. Right click on the WSDL, you will find "Generate WebService" option if you select the WSDL to java options from there on it take care of adding the required axis jars to the project and gets you the complete service code!