The rest of your attention will naturally be on your body and the environment.
Again, sit for a few minutes with the posture and the environment and with your breath. In and out. In and out. Sometimes this is quantified as 25% of your attention on your breath. The point isn't to get it "right," but instead to give you an idea that you're not channeling all of your attention tightly on to your breath. The rest of your attention will naturally be on your body and the environment.