Retrieve Tasks from Workflow Repository

We are using webMethods products and researching how to utilize webMethods Workflow APIs.
May be you may answer some of our questions.
There is little documentation on the subject. Do you know any good resources on using Workflow API?
There is com.wm.zeus.pd.pdclient.api.*. What .jar file contains that package?
Here is the problem we are trying to resolve:
There is a business process: StartTask->WorkflowTask->EndTask.
webMethods creates instance of the priocess (instanceID identifies that and each step). When control goes to WorkflowTask, Workflow creates a task in the Repository.
Do you know if there is any way to retrieve Tasks from Workflow Repository that corresponds to instanceID of the whole business process?
Do you have any sample code to do that?
Any help is greatly appreciated.

… there is enough API javadoc for , please check the javadoc

> to create session: WFSessionFactory.createSessionGracefully(host, user, password)

> to start wf: wfSession.startWorkflow()

> to get your inbox: wfSession.fetchAllAvailable()

> to perform a task: wfSession.checkout(objTaskId);wfSession.commit(objTaskId, “complete”);

> close session: wfSession.close();

The problem is fixed by pointing to another wf server