If you're looking for playing rules (like a rule book), Ohio uses National Federation of State High School Association (NFHS) rules.
These rules are available on-line only to paid NFHS members (officials, school administrators, coaches, etc.). You can order actual printed rule books for any sport through the NFHS website.
I think that they might have a minimum order amout and you might not be able to purchase just one rule book. But check the website for more details.
Sometimes, you can find NFHS rule books on eBay or Amazon.
The Ohio High School Athletic Association does have rules covering administrative issues, like player eligibility, the number of games a team can play, when the official season begins and ends, etc. Those rules can be found on the OHSAA website.
The OHSAA modifies just a handful of NFHS playing rules and those few changes are also found on the OHSAA website.