To backup, if you're on cPanel login

1. Click Backups
2. Click 'Download or Generate a Full Website Backup'
3. Under backup Destination select Home Directory
4. Make sure your email address is in the email address box if you want to know when it's done
5. Click Generate backup

These backups can be quite big so either download the backup or make sure there is only one on the server at a time. To get the backup go to File manager (in the little window choose 'Home Directory') and you'll see the backup. Double-click the icon (double-click the name to rename the file) to download.