To Backup your Joomla! Website you need to have your FTP details ready. You need to create a complete Backup of all your Joomla! Files and also a Backup of your mySql database witch keeps important information for your site.
Use your FTP client to log in to your account using your FTP details to access your Joomla! files
Navigate to your Joomla! root folder, download the whole folder to your local Hard drive on your PC. Or you may want to zip/compress the folder and then download it.
You need to make a Backup of the mySql Database for your site. In order to do that you need to access phpMyAdmin or mySql Administrator. phpMyAdmin interface should be available in the cPanel for your account.
Look for the Icon “phpMyAdmin” and click on it. phpMyAdmin interface should now open.
Select your sites mySql Database on the left hand site of the screen in the Drop down box. Click on the Export button. Highlight all the Tables. Check the checkbox Save as file. Click on Go and your Database will be downloaded with extension *.sql.
To import the mySql file again, in phpMyAdmin click on the import button, if the import button is missing, click on the SQL button. Choose the sql file that you wish to import and upload it and the mySql Backup should be restored.