The basic structure is a table with Whats as the labels on the left and Hows across the top. The roof is a diagonal matrix of Hows vs. Hows and the body of the house is a matrix of Whats vs. Hows. Both of these matrices are filled with indicators of whether the interaction of the specific item is a strong positive, a strong negative, or somewhere in between. Additional annexes on the right side and bottom hold the Whys (market research, etc.) and the How Muches. Rankings based on the Whys and the correlations can be used to calculate priorities for the Hows.
House of Quality analysis can also be cascaded, with Hows from one level becoming the Whats of a lower level; as this progresses the decisions get closer to the engineering/manufacturing details.
A Flash tutorial exists showing the build process of the traditional QFD House of Quality (HOQ).