Setting up Multisite for all my sites so I can use the Cloner and other tools.

Hi there,

I can't find any clear instructions on how to set up the 'Multisite' feature. What prompted this is that I want to use the cloner tool to have a staging site for each of my websites that is easily accessible. I can't install the Cloner tool without the multisite feature. Is there any documentation on how to go about setting this up?

Thank You,
Mark