In order to set PHPList cronjobs you can use the Cron Jobs tool in cPanel. First log in cPanel and click on "Cron Jobs", then click on the "Standard" button and enter the following line in the "Command to run" field:

/usr/local/bin/php -q /home/yourusername/public_html/admin/index.php -p processqueue;

Please note that the path mentioned above should be changed to the full path to your PHPList application. i.e. you have to replace yourusername with your cPanel username. After that configure the cronjob to be executed on every 30 minutes from the menus below "Command to run".