Do a 'which php' to see if the cgi version of php is installed first. If not then you can use lynx if you have access to it to call your php script.
create a file called mycron.job and put in there:
- /path-to-php-cgi/php /path-to-script >& /dev/null
or if you use lynx:
- lynx url-to-script >& /dev/null
then do a 'crontab mycron.job' to install the crontab. Finally do a 'crontab -l' to make sure that it installed.
Search the web for how to set up cron jobs, because the above commands will execute every minute. Use it for testing only. And remember the only way to disable a cron job is to issue the command 'crontab -r' be sure to do that after testing. If you need more help let me know.