Hi There,
Here is the link to UML modelling documentation for netbeans
http://www.netbeans.org/kb/55/uml-index.html
Please note although netbeans 5.5 & 5.5.1 do have both UML and visual web pack, there is no connection/interoperation between the two as such, in my understanding.
UML documentation should make it more clear to you.
Thanks
K