Having a backup of your domain is a smart approach. All you need to do is to:
1. Log in to Plesk as Admin
2. Select the Web space you are using
3. Go to the Websites & Domains tab
4. Select Backup Manager
5. Click Back Up
6. Select either Server Repository or Personal FTP Repository where you want to store the data backup
7. Enter your Email if you want an email confirmation once the process gets completed.
8. Select whether or not you want the backup to include content.
9. Then, Select if you want the domain suspended during backup or not.
Note: (If selected and backup fails or takes longer than expected, your site will stay suspended and not accessible to visitors.)
10. Lastly, Click Back Up.