So, I just name all files with the .php extension and save them to the htdocs folder. Then to test the code, I open the main file (order.php, the one that does the posting in the example I cited) by opening my browser and typing in the URL field:
localhost/order.php
Then order.php should be able to post to process.php and the server will run the php code in that file and return a result to the browser window?
I think I've got it. Thanks again for your help!
Dick