Once you got your WordPress site the way you want it to. It is now time to backup. Hover over Tools in the side menu, and select Export. You would want to backup all of your content which will download a .xml file. I will give the .xml file a unique identification to help you know which file it is. In example of this site, my xml file is wp_fsp_fyi. If you should need to restore your site to this state, you would be able to do so. If you have multiple sites, you would want to back up all of the sites. Your files should download to your Downloads folder of your user account for your computer.