Updating an aggregate table from detail table using MLOAD (multiload) or job.

Hi All,
I am new to teradata and done some findings on FLOAD, MLOAD and manually creating a job to load data from 1 table to another.
I am able to do FLOAD, mload for loading the data from 1 table to another table.
The thing is
I am not able to update the aggregate table created from the detail table using mload, I am trying from last 4 days but with no success.
The detail table contains 1000000 rows and the aggregate table which contains the aggregated data from detail tables contains 99990 rows.
Now I need to update the aggregated table.
Is it possible using mload? If yes can you guide me the steps to do this?
If not, Is there is any other way to do the same?
 
Thanks & Regards
saumil sanghvi