You need to sit down with an experienced criminal defense attorney to discuss the specifics of your case and the new evidence that you wish to introduce. You can file a motion to overturn the judgment and get a new trial. Whether your motion can succeed will depend on a number of things including whether the Defendant was convicted at trial or plead guilty, the nature of the new evidence, and the reasons (if any) that the evidence was not available to be presented at the original trial. The time period is ASAP. The longer you wait the harder it will be to get any sort of relief.
You can reach Harkess & Salter LLC at (303) 531-5380 or info@Harkess-Salter.com. Stephen Harkess is an attorney licensed in the state and federal courts of Colorado. This answer is for general information only and does not create an attorney client relationship between Stephen Harkess or Harkess & Salter LLC and any person. You should schedule a consultation with an attorney to discuss the specifics of your legal issues.
You certainly should talk to an attorney if you can. Additionally, the law schools in Colorado (Denver University and Colorado University) may have clinics staffed by students who can help you with the process. You can check out the Innocence Project as well, they work with indigent persons wrongly convicted. Appeals take a long time and can be extremely complicated.
If you do decide to go it alone, try looking at some of the legal guides published here. Here is one I found: http://www.avvo.com/legal-guides/ugc/the-basics-of-post-conviction-relief-in-colorado
Best of Luck,
Shannon K. McDonald