If the Post is long then you can cut it by following way
Position your curser where you want to split the post between the teaser text and rest of article.
Click on the icon labled: Insert more tag
My curser is here … As you see, anything above the more line is displayed. Anything bellow the tag line is hidden, until somone clicks on the read more link. They will then be able to see the rest of the text.
When somone is interested to read more about the article, they will click on the more link and they will be able to read the rest of this text Here.