Research SSH, SFTP and SCP.
Back up your website to your local file system using one (or more) of the above protocols.
Once the content is local, back this up further into any cloud based system.
Document the full process you have taken and upload here for assessment.
You can supply your proof in any format, such as video or text. The choice is yours, however you will be marked exclusively on the content you supply and the detail within it.