1. Download the PHP script:

	# wget http://www.systmbx.com/scripts/sitebackup.zip

2. Extract the PHP file from the zip archive to your local drive:

	# unzip sitebackup.zip

3. Edit sitebackup.php. Enter the password you wish to use to protect the script and save the file:

	# vi sitebackup.php

	Line 11

	$password = 'mypassword';

4. Upload sitebackup.php to the root of your website through FTP or hosting file manager:

	# ncftpput –v –u "username" ftp.systmbx.com /home/systmbx/public_html sitebackup.php

5. Open your web browser to http://www.yourwebsite.com/sitebackup.php.

6. Enter your password in the text box and hit the Backup button.

7. Do not close your browser window. When the backup has completed you will see a link to download it.

8. Once you’ve downloaded the backup, delete fullsite.tar.gz from your website using your favorite FTP client or via hosting file manager.

Reference:
http://www.thewebhostinghero.com