First, create an entertainer by clicking a worked tile on the city screen. Then click on the entertainer that will appear in the city's population roster. This will turn the entertainer into a tax collector. (By clicking again you turn the tax collector into a scientist, and a third click will turn the scientist back into an entertainer.) Please note that tax collectors and scientists can only be created in cities of at least size 5.
I have to admit that a tax rate of 90 % just to cover maintenance is quite unacceptable. In addition to tax collectors (which are really "expensive" in terms of lost food and resources) consider establishing trade routes and (if your situation permits) changing governments.
Finally, it's nice to see that there are still people playing the original Civilization.