How to implement a class library?

Question

C++ / C#

Hey guys. At the university they gave a term paper on the topic - Make a class library in C ++ to implement some kind of algorithm (to choose from, be it a sorting or searching algorithm, etc.). Before that, I had never worked with C++ and did not teach it.
I’ll write the implementation of the algorithms + -, but I don’t understand what a class library is ((
Can you please tell me what to read, what to see?
Thank you very much!
PS do not throw stones)