Question : Running Sum

I am a newbie at VBA but I think I am trying to do something simple:

I have a table (Tbl_Transactions) with three fields ( Date, Type, Amount).  What I want to do is when a record is added to the table (will probably add the code to the After Update property), the VBA code will calculate and populate a running sum (I'll add a fourth field) which will update the new balance of the account as of that date.

How do I do this?  Can anyone help me?

Answer : Running Sum

'how would I write the code to sort by date and then by ID code '

It already does that.
I assume that you have added an autonumber ID field to your table.