REQUEST: Directory reading from PHP to Flash

I was hoping someone could post a tutorial that in which a PHP file would read the number of files in a directory (the directroy name being a variable so that it could check different directories). That number could be supplied to a Flash file via a loadvars or loadvariables.

What I am trying to do is set up a picture slide show in Flash, and I need PHP code supply that Flash file with the correct number of files in a given directory.

I know this is probably pretty simple, and that there are similar php codes on this site, but I have never touched php before and I need help in even the most basic php coding.

Thanks
Justin