How to get the largest and second largest group molecular mass datas in a crosslink polymer system?

Dear MS users
In paper"computing thermomechanical properties of crosslinked epoxy by molecular dynamics simulations" , Fig.4., author show a diagram about the molecular masses of the largest and second largest groups in a crosslink polymer system.
Question is, what are the operation methods in Materials Studio? How can I get these datas? 
I suppose this question can be simplified as "how to get molecular masses of all moleculars in a **.xsd file".

Looking forward to any help 
Thank you all.

Fang