You need to import config.php (or hard code the database variables from that script into your own) and then to connect to the database using the PHP function mysqli_connect() and use the handle returned from that in a call to the mysqli_query() function and use the return of that to call the mysqli_fetch_array() function.
To see how it all works look at the includes/ConnectDB_mysqli.php script.
Thank you!
All done, works like a charm! (improving the quick entry screen by loading product names next to the code to detect mistakes earlier during input)