Where is the battery located? After 4 years I want to know how to replace it. on 2007 Chevrolet HHR

The manual which came with the car has very little on maintence. I can't find the Tank for the rear window washer or the location of the oil filter in the book.

The battery for your 2007 HHR is located in the spare tire well in the rear floorboard. The rear window uses the same washer bottle as the front. The oil filter is under a plastic cover located on the topside of the engine just at the rear of the intake manifold.