Adding CSS class to fields (Content Types) I added a new content type with some fields

I have a field to upload image, I want to add a CSS class to this specific field,
Should I done it via node-file.tpl.php

or via the dashboard and where?
Try out Field Formatter CSS Class module.


  allows you to set any text/list/option/taxonomy field to render as CSS
  class on the node. This enables the node author to select predefined
  CSS styling per node.