Assigning Values to Nested Varrays

I'm new to this so some help would be greatly appreciated. I have a nested Varray datatype that has another Varray type in the object.  I can seem to read values from the database in a bulk insert into just the main object annot the sub array.  fro example:

SQL> desc USER_ACCT_ROLE_ARRAY

USER_ACCT_ROLE_ARRAY VARRAY(500) OF USER_ACCT_ROLE_TYPE

Name                                      Null?    Type

----------------------------------------- -------- ----------------------------

USER_ACCOUNT_ROLE_ID                               NUMBER

USER_ACCOUNT_ID                                    NUMBER

ROLE_ID                                            NUMBER

ACTIVE                                             NUMBER(1)

CREATED_BY                                         VARCHAR2(20)

CREATED_DATE                                       DATE

LAST_MOD_BY                                        VARCHAR2(20)

LAST_MOD_DATE                                      DATE

REGISTRATION_TYPE                                  VARCHAR2(10)