I am not getting money from my pcity every month. I am wondering what I need to
do to access it. do I need a town hall or tax office?

You will get income once the income reaches 50k, not every month.

To elabourate on the above. It works like this, each unti is independant in
terms of paying out cash, EQ the portal, the bank, the weapon smith, the
general store, the armouary. (there are for sure more i can only think of these
atm).
When a single installation reaches a certain amount of revenue (i cant remeber
exactly what amount), then this installation will pay out 50k divided between
all of the councilors who own the city (in your case if its only you, you will
get the whole 50k).
You can not use the monthly stock as an indiction of when you will get paid (or
at least i no real accurate sense), as each installation earns revenue at
castly difference rates depending on its use by players (EG , you will get far
more payouts from your shops than any other installation, simply because they
are used more and will earn their revenues faster)

If you ahve more specific questions you can also ask me in game

-Delve