How to show image in teaser of any content
Your sentence is not very clear but :


To display user's picture, add "author of the node" relationship to the view and "user picture" field, with the relationship.
To display post's picture, presuming it's in a distinct image field and not in the body, go to your display settings of your content type, in the teaser section, set the image as you want it to be displayed, it will then appear in your view.