There are multiple layers to backing up your WordPress website. Many people make the mistake of thinking that the WordPress export file (Tools > Export > filename.xml) is a full backup. It’s not, that covers your posts but does not include the photos uploaded to the posts or the configurations of the widgets and/or layout of your posts.
For a full manual backup, you’ll need to capture at least 2 things;
1) Download all files (using FTP)
2) Download SQL file (using phpmyadmin)
There are a number of ways you can do this depending on what kind of web hosting package you have. You can find a full reference guide on WordPress.org for WordPress Backups but you will more than likely find a video tutorial perfect for your situation on Youtube such as “GoDaddy Backup WordPress Website” or “HostPapa Backup WordPress Website” etc.
For a full automated backup, you’ll need a plugin such as;