Here is a quick tip on how to run crontab every 5 minutes.

*/5 * * * * /home/adam/script.sh will execute script.sh every 5 minutes.

Also, here’s a quick guide to understaning the layout of cron:
# MIN HOUR DAYOFMONTH MONTH DAYOFWEEK COMMAND
5 * * * * echo 'Hello'

Also, the Crontab Man page

For further reading on Crontab check out Understand Cron Jobs in 5 Minutes