To configure crontab in your system, you have to install crontab software on your system. You can use the below given command.
$ yum install /usr/bin/crortab
Now you can edit the file using crontab -e command and write down your program name you wants to run and save the file.
* * * * * date
Now this will run date command in every one minute. You can also write your program name accordingly.