Extra fields in article
You can show the fields with automatic plugin or follow this instructions.
In this case the id of extrafield is 1, we can get this number in the extrafield list. 
In the template folder we create a file html template.
For example: /templates/[our template]/html/com_content/article/default.php
Download and paste this file in your template folder. REMEMBER EDIT AND WRITE THE CORRECT ID EXTRA FIELD.
It's all.



