A few examples are supplied with the installation, that you can use to practice with and build upon.
All relevant files are installed, by default, into the installed directory folder, typically C:\Program Files\Autodesk\Moldflow Insight 2019\data\solverapi
Three examples each, for the user viscosity and user PVT API codes, and one user core shift example are provided, as described below. For each, a Visual Studio project file ('MoldflowUserFunctions_***Example.vcxproj' etc) is supplied to assist in building the 'MoldflowUserFunctions dll'. Build your library as a 64-bit Release DLL. Once built, the file 'MoldflowUserFunctions.dll' should be copied into the installed directory folder, typically C:\Program Files\Autodesk\Moldflow Insight 2019\bin