Notice: this information was written when Microthemer version 2 was current. On Dec 26th, 2014 version 3 was released with a completely new interface. Some of the information may be redundant, but as much of
the functionality remains the same in version 3 we haven't deleted this post.
How do I do that? I had to wipe my WordPress installation, and now I need to download another copy of the Microthemer plug-in to reinstall. Tell me how.