I'd recommend using the tutorials rather than just typing stuff and seeing what happens. The language and concepts are the same, but there are some big differences at the framework and platform level.

The xUnit tutorial is here: https://www.microsoft.com/net/tutorials/csharp/getting-start...

Those tutorials are pretty intro level, but they do cover some of the issues you ran into.

Also, I'd recommend checking out the new Visual Studio 2017 RC with updated .NET Core tools and support for the csproj based projects: https://blogs.msdn.microsoft.com/dotnet/2016/12/12/updating-...