To position the vertical floating buttons, you need to specify a location on the page by providing a vertical ("top" or "bottom") and horizontal ("left" or "right") position as style attributes. Look for the following attribute in the code you copied:
style="left:50px;top:50px;"
Change the values for "left" and "top" (or use "right" and/or "bottom") to specify an offset from the top/bottom and left/right of the page. For example, if you want to specify that the vertical floating buttons appear 200px from the left of the page and 100px from the top of the page, your code should look like:
<!-- AddThis Button BEGIN -->
<div class="addthis_toolbox addthis_floating_style addthis_counter_style" style="left:200px;top:100px;">
<a class="addthis_button_facebook_like" fb:like:layout="box_count"></a>
<a class="addthis_button_tweet" tw:count="vertical"></a><
<a class="addthis_button_google_plusone" g:plusone:size="tall"></a>
<a class="addthis_counter"></a>
</div>
<script type="text/javascript" src="http://s7.addthis.com/js/250/addthis_widget.js#pubid=[YOUR_PROFILE_ID]"></script>
<!-- AddThis Button END -->
Be sure to replace [YOUR_PROFILE_ID] with your profile ID in the above code sample.