That's EASY: you want one ounce of chlorhexidine & the rest of the 32 ounces is water, so just fill the bottle. (If your bottle holds exactly 32 ounces & no more, you'd actually end up with 1:31 but don't let that keep you up nights, lol. It doesn't matter.)
But- it's best to put most of the water in first, because the running water will cause the chlorhexidine to foam up a little & not allow you to add all the water to dilute it properly. Make sense?