This is the answer to "can you have a look before I put it up". The link shows exactly what you are seeing in the editor, on any device, without them signing in or installing anything.
It is the right tool for a second opinion, for showing a business partner, and for a developer showing a client work in progress. It is not a way to run a private website: the link is unguessable but it is not protected, so anyone you send it to can forward it.
Step by step
In the editor, press Share preview.
Copy the link it gives you and send it however you like.
They open it in any browser and see what you see.
Keep editing. They will see your changes when they reload.
If it does not go to plan
Is the link private?
It is unguessable, but anyone who has it can open it. Treat it like a password: fine to text your business partner, not fine to post on Facebook.
They say the link is broken.
Preview links stop working once the draft they point at is gone. Make a change and share a fresh one.
Will Google find it?
No. Preview pages tell search engines not to index them.