matching with notepad as database

Question

we are developing an app that uses "notepad1.txt" and "notepad2.txt" as our databases. we used a schema (.ini file) to manipulate the data inside. our tasks are the following:

FILTERING:
- be able to filter each notepad according to their fields (completed) :)

SUBTRACTING: (completed) :)
- subtract the "amount" of some certain entries with the same "transaction number" in notepad2.txt

MATCHING: (not completed) :(
- create a dataset which contains filtered entries from each notepad. (ds1,ds2)
- match the 2 datasets which have some similar fields
- display the entries that are found in notepad1.txt that is not found in notepad2.txt in a separate datagridview
- display the entries that are found in notepad2.txt that is not found in notepad1.txt in a separate datagridview
- view the matched entries in a separate datagridview.

kindly help us with the syntax that will be useful for us in matching

thank you for helping
:D WE ARE DESPERATE