Author not displayed on posts in twenty eleven

I want to know, too!

Twenty Eleven does show the author in the ‘posted on ..’ line by default;
and it is in the html code of your front page; for example:
<span class="by-author"> <span class="sep"> by </span> <span class="author vcard"><a class="url fn n" href="http://www.existentialbuddhist.com/author/sethsegall/" title="View all posts by Seth Segall" rel="author">Seth Segall</a></span>

something in style.css must be hiding it;

this line:

.single-author .entry-meta .by-author {
	display: none;
}

this is a (debatable) ‘feature’ of Twenty Eleven – not to show author info if the whole site is only posted by one author.

in your child theme’s style.css, add:

.single-author .entry-meta .by-author {
	display: inline;
}

if you don’t have a child theme, edit style.css and either remove these lines or change from ‘none’ to ‘inline’;

however:
it is really recommended to use a child theme of the (default) theme Twenty Eleven;
a: to avoid that the modifications are overwritten with the next upgrade of your wordpress version;
b: to have a ‘fall-back’ theme if you have any major problems with themes in your installation.

This solution added the author name to the bottom of the post, but I’d like it at the top with the date. Any solution for that?