Trying to setup a cron job

[nicuz]

I am trying to setup a cron job for my website, after this tutorial:

Type crontab -e
Ok now type 'i' and input something similar to: 30 * * * * /home/virtual/site/fst/var/www/html/cron.php.
Now push Escape then type :wq (it tells it to write the changes and then quit). It should say 'installing new crontab'.

I did all of this,the message"installing new crontab" showed up but for some reason it does not work. Anyone has any ideas? Do I need to put a code in my script cron.php?

Thanks

[jatar_k]

that should make it run every 30 mins

It didn't do anything?
What is the script supposed to do?