title: Users accept the challenge (wordpress data logic)
body: <p>I'm working on a project and do not understand how I can relate data between users and post in wordpress. It is about creating a custom post that challenges users to do "something" and users decide whether to accept the challenge pressing a button (for example). I would understand the logic of data to then create querys of relations between users and "challenges".</p>
  
  <p>Could you guide me how to relate many users to a post? ¿Custom fields?</p>
  
  <p>Thank you!</p>