Sorry for the confusion. The link to the theme you mentioned and the version of it that is available on WordPress.com are different. At WordPress.com, you can use CSS with the Custom Design upgrade to adjust the appearance of things on the page, but you cannot change the underlying structure. Here is an approximation for how to add a little info into the sidebar. It works by using some HTML you can add to posts. The HTML can contain whatever you'd like to put in the sidebar and it will have a unique ID so you can style it using CSS. So, for example, you could add this HTML into a post:
<div id="movetosidebar">
<p><strong>Availability:</strong> print only</p>
<p><strong>Word count:</strong> 2,800</p>
</div>
Then you could style that HTML and move it to the right using absolute positioning:
#movetoright {
position: absolute;
right: 15px;
top: 210px;
width: 145px;
}
#movetoright p {
border-bottom: 1px solid #CCC;
}
The only down side to this method is that you have to place the block manually, and that means that if you use a ton of tags on one post and not on another, the spacing could look off or the elements could overlap. So, this solution is really only best if your posts all use generally about the same space for tags on each post where you add the HTML blog that goes under the post meta
Or if you would prefer to have more control or a setup like the one you linked to, then you could switch to WordPress.org.