I'm now a guy with a compressor

There should be a pressure switch that turns the motor on and off. This controls the range of pressure in the tank. This is probably set at the factory and you shouldn't mess with it unless you really need to.

Then there is the regulator which decreases the pressure in the hose for things like paint spraying. Where you set the regulator depends on what you're doing.

When I built my compressor I plumbed two separate outlets. One goes through the regulator and a dryer. The other one comes straight off the tank.

Most of the time I use the one that comes straight off the tank for things like sand blasting and running air tools. My compressor cycles between 90 and 110 psi which is fine for the air tools.

When I'm spray painting I move the hose to the other outlet and set the regulator at 45-50 psi.