This video demonstrates how a user with the "Author" role can create content, create new revisions and move the content to the "Needs Review" state, but not publish the content.
I'll login as "Author" and create a new article. I'll select the "Exhibits" section, and you'll see that the default moderation state is "Draft" as per the Article content type settings. Because I can move content to the "Needs Review" state, I could also choose that here as well, but I'll leave it as Draft, and save the content.
Creating a new draft
We're taken to the "View draft" tab, and given a bit of information about the current revision. We see that its state is "Draft", and that this is the current draft. If we click the "Edit draft" tab, we can update the body of the article to something more useful. Again, we could move this to "Needs Review", but I'm going to do that in the "My Workbench" dashboard. So, I'll just save the new draft.
Moving content to "Needs Review"
Now, I'll click the "My Workbench" tab, and then click the "My Drafts" tab. I'm ready to move this to "Needs Review", so I can simply click "Needs Review" in the "Moderate" column. Now, because I do not have permission to move content from "Needs Review" to any other state, I don't have any options in the "Moderate" column. I can however, click the article title and edit the draft. I'll do that. And this time, even though I can edit the draft, I don't have the option to change the state because it's in "Needs Review".
Now I'm going to go back to "My Workbench" and switch to the "Editor" user.