Setting up cron on your server
Use crontab -e to edit your cron jobs. To run a daily cron, add a line like this:
0 3 * * * /bin/sh /path/to/magento/cron.sh
This will run at 3 AM every night.
For log cleaning, you can check /path/to/magento/shell/log.php.
Set up cron in Magento
In the Magento admin, go to: System > Configuration > Advanced > System > Cron (Scheduled Tasks) and configure cron jobs you wish to run.
You should know that Magento runs cron jobs even if you don't have a daily cron job configured. Whenever Magento receives a request, it checks if there are any cron jobs to be run. Therefore, having the daily cron job would only make sense if you had no requests for an entire day.
Really there is no next step to be done. I recommend you read How to Set Up a Cron Job.
