C# is a modern, object oriented language developed and maintained by Microsoft. The learning curve is small, reduced even if the developer has experience with other 'C-Style' languages.
C# is a carefully designed language with lots of great features, such as type-inference and async/await. The official documentation is very extensive and well-written.
Although .NET used to be Windows-only, with the release of .NET Core you can also use C# on Mac or Unix-based systems.
If you've downloaded the command-line client and have C# installed on your machine, then go ahead and fetch the first problem.
exercism fetch csharp
In order to be able to submit your solution, you'll need to configure the client with your Exercism API key.
exercism configure --key=YOUR_EXERCISM_KEY
When you've written a solution, submit it to the site. You'll have to configure the command-line client with your exercism API key before you can submit.
exercism submit PATH_TO_FILE