How do I print in two Colors - XYZ DaVicni Duo Printer

I can't seem to Print in two Colors...I have a printer with two Nozzles.
I made a three d model Assy in Solid works...the Model had two Different Colors.
I translated to a STL file...loaded up in printer...but the printer only recognized it as having only one Color.
it would only print it in one color....anyone have any Ideas?