Where do I put the oil in for a 2003 chevy trailblazer

See my response to your first question.

Read my response on your first attempt to ask a question here. Why do you feel you need to add oil? How often do you change the oil and how long has it been since you did it? Depending where you go, some service centers will check the oil level free and if you need oil, add it. Your vehicle is 11 years old and if it is losing oil, you may have a gasket leak somewhere on the top of the engine. I have owned 4 Buick vehicles and 2 Pontiacs over two decades and they all had oil leaks from either the intake manifold or valve covers, never to be fixed no matter how much money I threw at it. The GM vehicles appear to be like Harley MC, if they don't leak oil, something is wrong. Great vehicles, some of the best made, but for some reason they can't hold their oil.