Step 3: Glue the fins and reinforcements.
Glue the tail fin and nose fin onto the body of the plane using the hot-melt glue gun. Insure the fins are aligned dead center of the body and not angled in any way. At this time, you can also add the other reinforcement strips. These are just strips of foam cut and glued along the bottom of the fins and along the sides of the propeller cut out.
Also visible (through the cut out) is one of the two fins on the far side. These two fins help prevent the propeller on this plane from damaging the opponent's plane. I'd suggest waiting to glue these on until the electronics are installed, it'll make it easier because the plane will sit flat on the table.
It's a good idea to apply a strip of low temperature covering or fiberglass tape to the leading edges of the plane. This is a vulnerable area and the covering or tape will help prevent rips and tears from impacts.