Summary Page Problem – Changing Photo Size

On my Website, it shows a directory of the post text and also a picture from the post. Can there be a method to boost the size of the picture that displays on the key page?

Thanks, Jessica

http://www.reddit.com/r/b0okworms/comments/2jn3yv/
http://www.reddit.com/r/b0okworms/comments/2jn3kg/