C# is a weird one to start with. I used Java and C in high school, and added Python and C++ during freshman year of college. I just graduated in Computer Science a couple months ago and haven’t used Java in years.
In any case, your goal shouldn’t be to master a particular language unless you really need to for a job. You can get a pretty good sense of what a language can do from a quick tutorial, then just practice implementing data structures or an idea you have (simple 2D games are a fun option) and look things up as you need them.
This might not teach you the most effective or clean way to program, but hopefully your university fixes that part.
Also note that this advice does not apply to functional programming languages like Haskell or OCaml. For those, you will need to understand how they work before diving in.