从内部方法添加到列表

I am new to Asp.net and C#, I am trying to log changes made to a directory. The problem I am running into is that from within my method which picks up changes made to a directory, I am unable to add the information (in the form of a string) to a list, listbox, or anything outside the method at all.I am new to Asp.net and C#, I am trying to log