My company has brought a Russian citizen into the country under false credentials and has given him all my responsibilities and "eliminated" my job. How do I report this to immigration?

You can report suspicious immigration activity (for the US) here:
HSI Tip Form (http://www.ice.gov/exec/forms/hsi-tips/tips.asp)

Your issue about how or why you were eliminated is a separate issue. If you believe that you were terminated unjustly, take that up with your local authorities.