title: How to create Categories in Rails
body: <p>i'm trying to Add Categories to my Rails app, but don't quite know how to do this.</p>
  
  <p>I have many Pins(Images) and want the user to be able to assign a category on those Pins.
  <strong>ASSIGN</strong> not create, edit, or delete a Category, just selecting one for their Pin.
  Meaning that, When a user uploads a pin, he can choose from a dropdown list a Category.</p>
  
  <p>Then, another user can choose from the Menu a Category, and ONLY the Pins in this Category will be listed.</p>
  
  <p>How do i do this? Where to start ?</p>
  
  <p>Thank you</p>