Examples of cron tab commands. These may or may not work, you should contact your host if you aren`t sure. Make sure you use the correct paths.
/usr/local/bin/php /home/admin/domains/yourdomain.co.uk/public_html/cart/control/cron/product-ops.php
php q /home/admin/domains/yourdomain.co.uk/public_html/cart/control/cron/product-ops.php
/usr/local/bin/php q /home/admin/domains/yourdomain.co.uk/public_html/cart/control/cron/product-ops.php
C:\Windows\php\php.exe "C:\server\www\cart\control\cron\product-ops.php" (Windows)
If you don`t understand this, contact your host for assistance. Path is almost always the FULL server path to the cron file.