Welcome to the forums!
I'd start by familiarizing yourself with the various maps,
here. Next, review Colorado's
Summary Sheet before following the links to the Colorado Statutes.
In a nutshell:
1. Don't OC in either Denver city or Denver county. That includes the corridor leading to Denver International Airport as well as the airport itself.
2. If a building or area is posting either no open carry of firearms or no visual display of firearms, don't OC. Doesn't matter if it's a publicly-owned building like the town hall or a library or a privately-owned facility (includes a private home or business). Don't do it. Also doesn't matter if it's right or not! If you're cited, it's an uphill battle. If something's not right, it's a lot easier to fix it with a few well-written letters than duking things out in a court of law.
That'll keep you out of most trouble. If you have any questions, search the forums. If you can't find what you're looking for, ask away!