can a picture of the post be displayed on the main page?

for instance, the post structure is one picture, then a lot of word
what should I do if I want the picture(not excerpt word) showed in the front page followed by "read more"?
I guess I should modify the
<?php bfa_excerpt( 55, ' ...' ); ?>
But I am not sure which I should use to replace this one

I am not native English speaker.
Thanks.

by the way, the picture is linked, not uploaded locally , will that be a problem?
also, it would be great if the size of the picture displayed on front page can be re-sized.