How to show images in posts on the homepage

I know images can be shown in the slider by setting a featured image to a post, but if I put a sticky post on the home page and set a featured image it sets it as a 201x201 thumbnail at the side of it. What I want to do is have the image within the post actually display on the homepage - within the actual post that displays. However, it doesn't show up when I 'add media' to the post. Can anyone help please?