This is an extremely simple case, configured for Fill and Fill+Pack analyses, that you can use to practice with and build upon.
Double-click MoldflowUserFunctions_ViscosityExample1.vcxproj from inside C:\Program Files\Autodesk\Moldflow Insight 20xx\data\solverapi, to launch your compiler, or open it in a text editor to examine the code. This API is applicable only to the Flow solver.