The oil filter on your Chevrolet HHR is accessed from the top side of the engine. It does not use a "spin-on" type oil filter. The "cartage" oil filter is located at the lower left rear of the engine. There is a black cover which unscrews using a 1 1/4 inch socket. You will need to unscrew the top and the filter will come out with the top. Don't forget to dispose of your used filter and motor oil correctly.
my 2006 hhr oil filter is on the right side front of the engine on top. when you open the hood look to the right on the front of the engine you will see a black plastic 1 1/4 " hex head on it. its' not a spin on filter it is a canister. go to auto parts store and get a filter and it will give you an idea of the size of the black hex lid you are looking for.