I am new to windows app and sorry if my question is very basic. I have a windows app(basically a web app) . I would like to open it and see in a emulator now.
The .sln file is the solution file, is the one Visual Studio opens. The error tells you that the file Medinet.csproj that is a project file can't be opened, the solution is ok, but you have a project with problems, check if your visual studio have installed the options you need.
In visual studio open Tools -> Get tools and features and check you have all you need like the Universal Windows Platform development and so on.