1)  Fold the sheet in half. Fold the corner in with a diagonal at an angle just a bit over 45 degrees relative to the centerline. The gap labelled "A" in the picture is about 1/4".
If you're using paper with an aspect ratio longer than 8 1/2" x 11", or if you want the wingtips to end up shorter than in the Classic Dart, it's okay to make this fold at 45 degrees (A=0) just like in the Classic Dart.
Flip the plane over and fold the other corner in to match the first.
2)  Create the leading edge of the first wing with the edge of the flap about 1/4" past the centerline (rather than directly aligned with it as in the Classic Dart). This overhang is key to the E1 enhancement, which may be applicable to other designs as well as the Dart E1.
2001 PaperAirplanes.net