This provides a Revit API programming template for using external data. This template (ExternalDataFromExcel) provides a class as an example on creating an excel file from scratch and fill it with the information from your Revit project and change the format and style of cells inside the worksheet.
The Second class in this template, provides you an example of reading an existing excel file and use the values of each cell in Revit project.
The third class, is the same as the second class. In this class, we use the data from excel file and change the type parameters of a window selected by user in Revit project. In this class the user is asked to select a window and then the code gets the type parameters of that window. Then the code reads data from excel file and changes the window type parameters respectively. This class would be a good start for those who want to update their model in Revit using external data from excel.