PHP How to Open & Edit file in List Content of Directory.

Hello Everyone, I’m having a page php have function list content of directory in computer such as c:/folder after that I can open, write and save any file I want in list file. Now I have complete to list content of directory, now I want to click any file in list file of derectory to open in a textarea, we can view and edit file, then I have a button submit to save it. But I don’t know how to when I click to file name in list content of directory, it content have show in textarea, what event click to to it ?. Please help me. Thank very much.
Here is my code:
https://www.mediafire.com/?l3go25zl88359zu