As can be seen throughout the book, building financial models requires multiple skills.
First and foremost, it requires logical and analytical reasoning to gain a good understanding of the requirements for a financial model. Put simply, you cannot model what you do not understand.
Then, based on an understanding of what is required, the model should be designed and the project scoped out to reflect the requirements of the model.
Finally, some knowledge of spreadsheet software is required in order to develop the model ...