Thy this, Amy:

http://www.opserver.de/wiki/index.php/WMP

Scroll down to the English section.

EDIT:

Never mind. I had read WMP when I should have seen you were looking at WMB. However, if WMP can be exported from Blender, then it can me directly imported into WED and built as a WMB there. In fact, you would most likely want a WMP file from Blender instead of a WMB, wouldn't you? Because the WMB contains a lot of additional information like shadow map info, etc.