One very useful way of loading a collection of records is using the custom where clause. For example if you want to find a list of constituents who are born in a certain year you could write the following
Dim oRecords As New CRecords
oRecords.INIT SessionContext, tvf_record_CustomWhereClause, "BIRTH_DATE LIKE '1950%'"
This is the only really effective way of doing this without returning a list of all constituents filtering them in the code (much less efficient).