First, you have to understand the difference between backing-up your website just so you have a copy for when something goes wrong with it and backing-up your website so you can move or transfer it somewhere else. The latter is technically called "migrating" your website. This FAQ will deal with the former, making a copy of your website for safety's sake.
Depending on the web hosting plan you signed up for, backups might be included. But, usually the steps are not that straightforward to restore a backed up site. But, there is a simpler way you can use, in addition to the backup services your web hosting provider offers.
And, your if your hosting plan does not include backup services, or if you have to pay extra from them, then you definitely need this method.
We advise you use the free UpdraftPlus backup plugin:
It is very highly reputed and easy to use. You can set it to backup your site every day, a few times a week, once a week, etc. It also allows you to send the backup to wherever you wish, e.g., to your Dropbox or other cloud storage account, or to your email account. And, restoring your site is a fairly simple and straightforward process.
We highly recommend you get this and use it right now so you have a backup of your site as it is today, i.e., before you start doing any more work on your site.
(Again, please keep in mind that the plugin allows you to backup and then restore your site to is original location (domain). If you wish to move your website to another location (domain), this process is called "migrating." You can find out more about this process in another FAQ.