Well, you can! With a bit of html...
Remember, this only works when you type - or copy-paste - your text into ordinary text area. Anyways, the Editor link on the right top side of the input area is hidden when you are using html.
OK, let us start with ...
1. Right Side Column With Text
Right side column
Left side column
The Code
<div class="pull-right">
Right side column
</div>
Left side column
2. Right Side Column With Image
The Code
<div class="pull-right">
http://i.imgur.com/LVTwnCs.png
</div>
Left side column
3. Left Side Column With Image
Right side column
The Code
<div class="pull-left">
http://i.imgur.com/LVTwnCs.png
</div>
Right side column