Some standardized forms can be accessed at http://www.courts.state.co.us/Forms/Index.cfm, or the court clerk's office might have a standardized form. If neither of those resources have the form you are looking for, then there is no approved form specific to a 35(b) and you will have to use one of the generic motion forms available or retian an attorney for assistance.
Notice: The information contained herein is intended as general legal information and does not create an attorney-client relationship and is not governed by confidentiality rules. This general legal information is not a substitute for seeking the direct advice of legal counsel.
The state judicial website and the appendix to the Colorado Rules of Criminal Procedure do not have a form motion for reduction of sentence. This is probably because the information to be included in such a motion is unique to the defendant. Even though there is not a form, you should follow the rules regarding the caption and formatting required for motions. See Appendix to Colorado Rules of Criminal Procedure (referring to C.R.C.P. 10).
Both the previous answers shed light to your legal problem. You can get what needs to be included on reading the specific rules and applicable case law. The information required for a successful 35 (b) motion is very fact driven with strict timelines.
You need to consult with an attorney to help you and just got to accept that you may have to pay the required fees if you want the legal services just like anything else in life.