You mean you created a new project? Of course it’s normal that it’s empty, especially if it’s a command line app - there’s nothing to be seen initially.
If you specifically create a new Windows Forms application, you should get an empty visual window (onto which you can drag form elements).
If you mean you opened the C# client above into Visual Studio, that’s normal too - the client does not have any visual things to be shown. It’s a library, to be included as part of other projects, potentially visual ones too. You could only see the code itself, if you double click on the specific file you’d like to see the code of. The list of files and projects should be visible from the right.
The file you should be trying to open is either the .sln file, or from inside Visual Studio, open the different .csproj files.
Different API clients do it their own way, and many simply don’t have any documentation beyond source code documentation, and even those that do would assume familiarity with creating interfaces, rather than guiding you all the way from creating a blank app, to filling it with GUI elements, connecting and hooking the output to GUI elements. Everything short of doing the connection and the command, you’re expected to know in advance.
If you’re good with C# itself, you should have no difficulty getting started without tutorials, thanks to C#'s strict typing.
You’d simply find out the name of the “main” API class by simply using your common sense (but to save you some time with the above client: “Connection” is the main class, type “Command” being the thing to send with the “ExecuteCommand” method), and follow things from there by seeing what methods are there, what arguments they accept, and how would you initiate an argument of the specified type.
Heck, even with my API client, my docs, while very extensive, assume basic PHP and HTML knowledge. The docs don’t guide you about how you’d create a web app from scratch, that happens to use the client. I very much welcome others to write such tutorials and articles, but the place for those is not within the API client’s docs.