Using MARTE GQAM stereotypes in Papyrus UML models

I'm trying to stereotype some elements of my model with MARTE GQAM stereotypes, but I'm having trouble assigning values ​​to some of their properties. For example, I stereotyped a message between two life lines as <>. I would like to assign a value to the hostDemand property, which should be an instance of NFP_Duration. I do not see how to use the Papyrus editor to create an instance of NFP_Duration and assign it to the hostDemand property.

Yours faithfully