Try Google:
https://www.google.com/search?q=export+nook+st+notes&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US
fficial&client=firefox-a
Not relevant to you, but I rooted the Nook ST and use Coolreader and Aireader and I can annotate and export notes directly to a text file. Very easy.