Cron Job -- Permission denied

I tried to setup a cron job in my cPanel, but response email, this is what I get each time the script runs.

/bin/sh: /home/username/public_html/ss.php: Permission denied

How do I fix this?

Have you tried changing the file permissions to 775? Though 777 is good but its dangerous. Alternative, have you tried asking your web host?

Ok, I have done that, thought I no longer get the previous error, but I still het some errors, Or am I not doing the right thing… Now Please tell me how to make a script, let say ‘script.php’ that was uploaded to /www root folder to run by 8:15 am everyday using the Cron Jobs Icon on cPanel?
Please help me

Its working now, but I will like to know the difference between these command:
-a
-f
-q
as in php -q /home/USERNAME/public_html/MyScript.php
or php -a /home/USERNAME/public_html/MyScript.php
e.t.c.