hi nina :)

Hi there - static margin for a flying wing can be a bit tricky to explain, but Mr Deperrois does a good job in his paper http://www.xflr5.com/docs/XFLR5_and_Stability_analysis.pdf

I'd really suggest downloading XFLR5 and having a play around with it.  There is at least one tutorial on YouTube to get you started to using it.

If you want to do hand calculations, have a look at this spreadsheet here http://www.rcgroups.com/forums/attachment.php?attachmentid=3905587

Good luck!