Assign Values from a range to a range

Hi all

I'm hoping someone can help me out here, I'm not used to using excel
and was hoping there is a quick easy solution to my problem.

I have 2 tables in an Excel worksheet, one above the other, one is a
cumulative total, and the other is a weekly total, both the tables
will have corresponding rows and columns in the other table.  They are
basically an exact copy of eachother.

What I want to do is add the values in the weekly cells to the values
in the cumulative cells, such that each time I update the values in
the weekly cells the values in the cumulcative cells are incremented,
and I don't lose the previous weeks' increment.

Does anyone have any smart ideas, I'm quite happy to use VB, I just
don't know where to start.

Thanks

Madeleine