Write to a file with PHP (creating a visitors log file)
Heres a tutorial on how to write to a file.
You can write to a file in many differnt ways in PHP. You can overwrite the file each time you write to it, you can add to the end, and write to the begging of the file. You could also write anywhere in the file but thats a little more complicated than the rest so I'll leave that for now.
http://www.good-tutorials.com/tutorial/21819/write-to-a-file-with-php-creating-a-visitors-log-file-
