You sound like me, just last year as I went from avid Mtn biker to roadie (my first bike was a Bianchi too). I did a few centuries last year, this year I have raced a few times locally.

1. Go to a local club or shop ride on any given Saturday (Team Evergreen, Schwab, etc.,) and ride with those folks.
2. Try the meridian practice crit near the tech center.
3. Join the Meetup.com group Front Range Cycling (I think that is what we are called) and come to a ride. Every Monday and Thursday night we ride up Lookout Mtn.
4. Show up early for ERock, or other century ride and take off with the hard core folks.

Of the four, only the last one will cost you $$ and I probably wouldn't do this. All of these options will give you an opportunity to ask questions of locales and you can gauge your fitness. I don't think you should just show up to a race and have at it, you might get killed. People in Colorado love talking bikes, gear, racing and you shouldn't feel uncomfortable asking anybody, whatever. You can't ask questions going 100% into a corner among 10 other guys, so build a knowledge base first...probably why you are on BF

PM me if you want more specific and detailed answers.