How to upload an attached file
To upload the file, click Add in the WordPress toolbar. This file will become part of the post or page to which you added it. It will be uploaded to your website’s media library. If you upload a file directly to the media library, it is not automatically linked to a specific page or post.
Some WordPress themes display a list of linked posts on pages and articles. Most topics don’t show it. You can find out if a file is attached to a particular article or page by clicking on it in your media library . The Attachment Details window opens. The title of the article or page to which the file is attached can be found in the lower right corner of the Uploaded to line.