Before start config Windows Live Writer for Umbraco, make sure the Setting->Templates->Master page has following line in <head>:
<link rel="EditURI" type="application/rsd+xml" href="/umbraco/channels/rsd.aspx" />
<link rel="wlwmanifest" type="application/wlwmanifest+xml" href="/umbraco/channels/wlwmanifest.aspx" />
And create correct Content Channel (Name, Start Node in Content, Start Node in Media Library)
Then you can start fill homepage with http://ericguo.3322.org/dotnet.aspx and user name and password, select Metaweblog API and fill http://ericguo.3322.org/umbraco/channels.aspx as meta blog api URL in Windows Live Writer Tools->Accounts now.
Click finish button, you may find duplicate hostname in HomepageURL which lead to get theme failed, you can fix it by run regedit & goto HKEY_CURRENT_USER\Software\Microsoft\Windows Live\Writer\Weblogs, find the right name, in this case "dotNet" and correct the wrong HomepageUrl (usually duplicate in hostname).
Goto Live Writer again and in Tools->Account->Editing->Refresh Theme, now that will get correct theme from site now.
That’s all done :-)