How can I get a complete understanding of C# here on Sololearn?

Question

I finished the C# course. I'm realizing that, while helpful, it didn't give me a COMPLETE understanding of C#. I'm guessing the other languages on here are the same.

what I mean when I say complete is by getting a grasp of all, or all useful, word and operators in C#. I don't mean anything overly extensive but something more "professionally" extensive.