There are many plugins out there that will completely backup your site for you but here is a step by step guide to backing up your WordPress website with a FTP program and phpMyAdmin.
STEP 1. Back Up Your WordPress Website Files
First, back up your WordPress website files using a FTP program such as FileZilla which should look like the example below.
You need to connect to your host with FTP details supplied by your host and copy all the WordPress files under your public_html folder to a folder on your computer.
Do make sure you can see the .htaccess file as it can sometime’s be hidden. Refer to your FTP program’s help file to have it display hidden files if you are unable to see this file.
If you have a lot of Media content, this could take some time but while you are waiting, process with the next step to export your WordPress database.
STEP 2. Export the WordPress Database
Exporting your database is a simple process that only requires a few steps to complete.
Select the database that contains your WordPress website from the list on the left hand sidebar and then click on the Export tab on the navigation menu.
Note: Your Database name will be different to this example
The default settings of a Quick export and the SQL format for the export are sufficient for what we need. Click the Go button and the database export process will begin and a file will be downloaded to your local computer.
Once the database export and the FTP transfer of your files have both completed, you now have a backup of your WordPress website that you can use to restore should anything go wrong.