Newbie- seemingly simple search on a custom record type

I have trolled the forums for a while and always learn something. This is my first post and while I have been using NetSuite for about 2 years my experience in scripting is nil. I am trying to cobble something together without having my engineers modify the web application we sell.

We measure our customers' usage of a web application. For example, customers purchase 1,000 uploads, and then each day they may or may not perform some number of uploads into the web application. Currently-- the part I am not able to move my engineers on -- I get a daily file emailed to me from the web application. The file contains two columns: "Customer ID" and "Usage Qty", where "Usage Qty" is the amount that I am trying to deduct from a pre-purchased quantity.