OK, at the posting Tutorial it says
It only appears in your post if you have changed the index.php template file to display the Excerpt instead of the full Content of a post.
and
For more information, see Excerpt.
If I go to the link suggested it says
An excerpt is a condensed description of your blog post and refers to the summary entered in the Excerpt field of the Write Post SubPanel (see Advanced Editing). The excerpt is used to describe your post in RSS feeds and is typically used in displaying search results. The excerpt is sometimes used in displaying the Archives and Category views of your posts. The Template Tag the_excerpt() can be used to access the contents of this field.
An excerpt should not be confused with the teaser which refers to the first 55 words of the post’s content. When typing a long post you can insert the <!–more–> Quicktag after a few sentences to act as a cut-off point. When the post is displayed, the teaser, followed by a hyperlink (such as Read the rest of this entry…), are displayed. Your visitor can then click on that link to see the full version of your post. The Template Tag the_content() can be used to display the teaser.
Related articles: Customizing the Read More.
But nowhere does it tell me how to edit the Index file as desribed in the first part??