To add a cron job you would simply log in into cPanel and find Cron Jobs.
First, your script or software will come with their own command line you would use. Simply copy and paste this in the field called "Command Line" and your all set. If you would like to specify what times the command will run you would simply change the "*" in the entry to a number which would represents the minutes, hours, days, etc.
To edit the time, view the following:
0 * * * *
In this example, the 0 * * * * represents when the job should happen. The "0" in the example represents minutes - in this case "Zero" minute, or top of the hour. (If the number were 10 for instance, then the action would take place 10 minutes past the hour.) The "*" represent hour, day, month and day of the week. A * is a wildcard, meaning "every time."