I am also not very experienced in database but I have been fiddling with it for some time.
Try to do the followings:
1. Try to have only one table for all of your data. It makes life very easy for calculations and generating queries.
2. Create a simple form and put two Text boxes on it one with label say Month and other say Office No. Note down the name of each Text box.
3. Create a query and select all the relevant fields on to query grid. On the month column in Criteria row put the referenc for the month Text box from the above Form. Say if the form name is Form1 and Text box name is Text10. You would put the reference as [Form1]![Text10].
4. Similarly put the reference for office no under office no column.
5. Generate a report on the base of above query.
6. On report footer you can put a simple formula giving total for that month, like =Count [months]
7. Put a command button on Form1 that would open above Report
Hope this all makes sense and works for you.