I have a coolant leak and I don't where it's leaking from. How can I do a compression check or find another way to find the leak?

 

I have no idea what you mean. If something is leaking you can see where it is leaking from.
Do you, maybe mean that coolant is disappearing? There are only 3 places for it to go: the ground, the crankcase and the exhaust.
Pictures might help.

A compression test might tell you if there is a valve, ring or head gasket leak. As how to do it; rent or borrow a tester from your local auto parts store and follow the directions.

Is the oil level increasing? Is there a lot of water in the exhaust? Is there a puddle under the car?

 

Use a pump and pressurize the system.
https://www.harborfreight.com/radiat...kit-63862.html

 

There are possible leak points of coolant at the water pump, the hoses, the heater core, the radiator, the head gasket, the coolant recovery tank and the rad cap tee in the upper rad hose, so let’s start easy, look at the engine spot the wet area and take a photo, post it here and we can help. Remember gravity plays a major role here.