Break 2 graham crackers in half so you have 4 pieces. Those will be the sides of your house and the roof.
Using a bread knife, place a graham cracker onto a cutting board. Carefully saw the graham cracker so you don't break it. Cut the cracker from the corner to the center line and repeat so you have a triangle tip. Repeat so you have 2.
To assemble, place frosting into a pastry bag and cut a small tip, about ⅛" into the bag. Place a "triangle" house side onto a plate. Pipe frosting on the edges of the side of the house and place it onto the side of the house. If necessary, use something to prop up the side or work with a partner to assemble it. Do the same on the other side. Affix the "triangle" house side to the house. It shouldn't be perfect at this point.
Pipe frosting onto the bottom of the house and pick it up and place it onto the plate to secure it. Adjust the sides so they line up correctly. Pipe icing onto 3 sides of one roof piece and place it on top. Repeat with the other side. Make adjustments as necessary.
Using frosting, pipe decorations onto the house and plate as desired.