How/who To Contact To File A Wage Complaint Form In Colorado?

My past employer is with holding $100 from my last paycheck from over two months ago. They with held $160 until I returned a work shirt and after I returned it they only gave me $60 and are refusing to give me the full amount. I would like to report them to the correct legal entities and file the correct forms as well as notify the IRS (if that’s an option) in order to be a thorn in their side. Would love some advice and help on this, thank you.