Update map Object

I have an STL map declared:
struct CLIENTSTRUCT
                                  // Individual Department info
  int    clientKey;                                // ClientKey
  int    enrollKey;                     // Enrollment ClientKey
  int    guarantorKey;                   // Guarantor ClientKey
  string clientName;                             // Client Name
} clientWork;
typedef map<int, CLIENTSTRUCT> CLIENTS;
        CLIENTS	 clientData;
        map<int, CLIENTSTRUCT>::const_iterator cIter;

   I have seccessfully been able to populate the map with initial data 
(via .insert), but I can't figure out how to _update_ the map objects.
Specifically, I need to modify rhe "enrollKey" and "guarantorKey" 
elements of various objects after I use .find and the iterator cIter.  
None of my references (nor google) points me in the right direction.  
Please advise  TIA