This is a C# site so our focus is C#. That would imply that your are most likely using Visual Studio to create an ASP.NET application. You can target .NET Framework or .NET Core. Given that Microsoft is moving away from the former and towards the latter, I'd suggest going straight to the latter, as long as your intended host supports it. If you choose .NET Framework then you have the option of Web Forms or MVC. Web Forms was easier for many as it was more like Windows Forms but that paradigm doesn't really suit web development all that well. MVC requires you to take responsibility for a bit more of the detail but is more natural for the web. If you target .NET Core then MVC is your only option. If you go this way then you will need to understand C# fairly well and HTML to a reasonable degree. The views in MVC are Razor pages that are HTML-like in their structure and can contain straight HTML constructs. You will also need to understand JavaScript and CSS to do anything advanced. Most useful web sites are backed by some kind of database and the two most common are probably SQL Server and MySQL. SQL Server Express is free to use and integrates well with Visual Studio for development purposes but a full SQL Server license isn't cheap, so a host is less likely to offer that free. MySQL is open-source and many web hosts use it because it is free to them, but it is more of a hassle for you to setup in development. Either way, you'll need to be able to connect to and query databases, so some SQL knowledge is important and an understanding of ADO.NET or some ORM like Entity Framework. If you use an ORM then you may not have to write any of your own SQL but understanding how the ORM is mapping your code to SQL behind the scenes is a good thing.
