Templates files that you need to edit you can find in:
- Design->Templates
- From "Most common templates" list choose /node/view/full.tpl
- From dropdown list choose your Siteaccess name and click "Set"
- Edit article_full - Apply changes
Andrew, here you can find some information about template overriding http://ez.no/ez_publish/documentation/customization/custom_design/override_templates