"Bash" sprsheets/tbles to produce non-matching fal

Please help! I'm in a desperate predicament. I have several Excel spreasheets from separate sources. The spreadsheets are all slightly different, but have a common field, "PO Number." I need to "bash" the 2 vendor spreadsheets against the 3 company spreadsheets using "PO Number" as the primary key. The "bash" should produce fallout that shows only "non-matches." I want to see the POs that are on the company spreadsheets and NOT on the vendor sheets. I've just been told that I need to do this in Access. I do have access on my PC here in the office, but have never used it. No training either.

I have managed to import the Excel spreadsheets to 5 Access tables.Can anybody help me? Thanks.

Stephanie