I think I was mistaken - I was under the impression that sharing buttons should appear on the right side of the page under the widgets, as sort of a "master sharing buttons" group that would apply to the whole site (as opposed to beneath each individual post). Or something - if that makes any sense.
That is possible too, but you would have to add it as a widget. You can add a custom html widget and add the code, like this for twitter. You can google how to do a similar thing for any other social networks you would like to share with.
Alternatively, you could download a set of social media icons (a google search will return plenty), upload the images to wordpress, place the images in the custom html widget, and link the images to your social media pages.
An example for a twitter button would be
<a href="https://twitter.com/#!/zhogan85"><img src="/path/to/image" alt="Twitter Icon"></a>
Post back if you have more questions.