After you set this up, you do not need to manually create the site map. Magento will create it whenever you want.
Before you can complete this task, you must have FTP access to your Magento site, that is, you must be able to upload, delete, and edit files in your Magento site.
You must also be able to create cron jobs on your web server. Most hosting services enable you to create cron jobs. You should check the help files for your host, and ensure that you understand how to create a cron job.
Many hosting services offer the cPanel application for managing your files on the host. If your hosting service offers cPanel, then you might find this documentation helpful: