MyBB Community Forums

I want to add a "box" or section on my forum that is only visible for users with 0 posts. 

In the box I want it to say: 
Members with 0 posts have a user title called "Lurker" and lurker's first post is moderated (has to be approved by a moderator). 
After their first post, their posts will no longer be moderated and will have a "member" title. 

And I'm also wondering how can I make their first post moderated? 

Thank you in advance! 

there can be different methods to achieve above requirement.

I'd prefer to use a plugin like Required Approvals for moderating x posts of a user

above referred plugin was coded for an older version of MyBB.
see replies here if there is a problem with installation of it

And Template Conditionals plugin can be used to display specific message based on conditions.

You can use code like below with the template conditionals plugin installed

<if $mybb->user['posts'] == 0 then>
message to show users with zero posts
</if>

in general, such code can be added into header template / showthread template of the theme

[see also this -> templates related guidance]