There are some basic instructions in Instructions for Java Environments (WSC)
Java environments access the API through Java objects that serve as proxies for their server-side counterparts. Before using the API, you must first generate these objects from your organization’s WSDL file.
Each SOAP client has its own tool for this process. For WSC, use the
Before you run
wsdlc, you must have the WSC JAR file installed on your system and referenced in your classpath.
The basic syntax for wsdlc is:
java –classpath pathToJAR/wsc-22.jar com.sforce.ws.tools.wsdlc pathToWsdl/WsdlFilename pathToOutputJar/OutputJarFilename
This command generates an output jar file based on the specified WSDL file. After the output jar file is created, reference it along with the wsc jar file (for example, wsc-22.jar) in your Java program to create a client application.
In your case the error is indicating that it can't find your partner.wsdl file. Is it in the current directory that you are running the command from? You should have downloaded from your developer edition org in a prior step from under Setup > Develop > API.
If is isn't in the current directory, you may need to add the full path for it in the command.