Take a look at Martin Hepperle's site http://www.mh-aerotools.de/airfoils/index.htm
site for more info on "Flying Wings" (two items down on the left side). Once you have reached the flying wings page, choose the linkes under "see also:" for a lot of basic stuff on stability of tailess aircraft.
Way over simplified
, you want to move your CG far forward (compared to a tailed aircraft) and choose a (reflex) wing, such as the MH-6x series, which has a positive CM over the flight envelop you will encounter.