turn the cylinder being tested onto compression so all the valves are shut ,and listen for where the air escapes, it may be the breather system if its rings, or throttle body for inlet valves, or exhaust for exhaust valves. take the plug out next door and see if that sees any pressure as it may be haed gasket ,but watch out it isnt leaking into that cylinder through a manifold! check if the coolant tank sees any pressure ,

loads of test to do that way , my kit shows a percentage of cylinder loss ,so you know how much is leaking.....