Backing up SQL Server databases has been documented in thousands of books, Microsoft documentation and blog posts since the product was released in the 90s.
I’m not about to try and tell you HOW to backup your SQL databases. Rather, I want to take you through the basic considerations of deciding what to back up, when, how often, etc. in clear language that non-SQL folks can work through.
Understanding how to take and tune backups is important; this is more fundamental advice.