Automatically detect text file encoding

Question

Hello everyone.
Would like me to try this code from the link below in my app.
Thanks to GitHub, this Class automatically detects the code page from the text file.
But I don't know how to call this class in my application, I don't know how to use this class...
For example, if my file is located in the path: C:\TestFolder\Test.txt, how can I detect code page of this file Test.txt.
He is asking for your help. Thanks in advance.

Link of GitHub class:
https://gist.github.com/TaoK/945127