If you are about to write a post or make a change to the content such as editing a post, then it is advisable to make a backup before and after you've done so.
Backups are also your first line of rescue should your website be hacked, or become corrupted in the event of a server crash.
BackupBuddy is the backup software I install on the websites I build. Although BackupBuddy can do a lot more than its name suggests, backing up is what we will cover here.
BackupBuddy = easy peasy
Log into your website. In the WordPress dashboard / backend, find and click on BackupBuddy's sidebar item, usually near the bottom /end of the sidebar. You will arrive on the BackupBuddy dashboard page.
In most cases a simple database backup is sufficient. This will back up text content, including references to new pictures, but not the pictures themselves.
If you've been adding pictures, then do a Complete Backup.
Additionally, it is recommended to set up an automatic backup schedule. In some cases this will be set up for you as part of the finishing touches I apply to websites, along with the security software I install at the end.
Should you wish to check if a schedule is in place, or modify an existing schedule, access the BackupBuddy schedules via the sidebar.
How often to set a schedule will depend entirely on how often you modify your website. If you make changes every day, then a daily database backup, and a weekly full backup should cover your needs.