At any point while working on your site, you can share it with people in your organization to collaborate on the content.
Before beginning to create your site you should make sure to secure your site so that it is not searchable.
Open the sharing permissions in the top right corner.
In the pop-out window next to the Published option click Change...
Change the Publishing Settings so that only specific people who you share your site with can view it once it is published and click Save.
To Share you content click Add People in the top right corner.
Add users by their email account into the sharing box. and click Send.
To give permissions click on the Down arrow next to a person's name and select the permission level.
To remove a person click the X next to a users name.