I think you mean how to integrate forms into your jBPM workflow.
Examples that helped me are
http://community.jboss.org/people/bpmn2user/blog/2011/02/21/jbpm5-example-for-forms-with-variables
and
http://people.redhat.com/kverlaen/install-gwt-console-jbpm.swf
A nice screencast, but it does not show where to locate the forms. The sourcecode of the screencast comes with the demo installation of jBPM