When I am trying to review a first post, I get:
Our system has identified this post as possible spam; please review carefully
NB : The post does not contain any codes or urls.
How to review it correctly?
It would depend on the post, naturally, but I assume you're talking about this one. That post looks perfectly fine, so you would choose "No Action Needed" (as another reviewer already has). If you're not sure you can always choose "Skip"