finds the number of fans of each team and prints them in CSharp

I have this question about Arrays, the concept is really simple but the problem is I don’t know almost anything about Csharp, I am trying to help a friend who cant understand English very will, I told him how to solve the problem but without coding, can you help me write the code? also the question wasn’t in English, I tried to write it as clear as possible:
The fan.txt file contains the name and team information (GS, FB, or BJK).
by reading this information; The program that prints the names of the GS holders in the GS.txt file, the names of the FB holders in the FB.txt file, the names of the BJK holders in the BJK.txt file, and also finds the number of fans of each team and prints them on the form.
Sample file contents are below.

Go to Source
Author: flowery