Pipe a dot: Use dots of icing piped to the back of the candy to attach individual pieces of candy to gingerbread. Pipe bigger dots for larger pieces of candy.
Pipe a line: Pipe a line of icing on the back of the candy to attach long candies like candy cane sticks or pretzels.
Pipe a small mound: For flat, stand-up decorations, pipe a small mound of icing (about the width of your decoration) and insert your candy decoration figure.
Place directly: Candy can be placed directly on freshly piped decorations such as garlands or iced surfaces, no extra icing needed.
Notes
Royal icing dries quickly once exposed to air. Place candies on your icing immediately to ensure that the candy sticks to the surface.
Use the same techniques for attaching sprinkles and sugars on the gingerbread house.