The Extended Properties form can be found in the Project Summary Info form.  This will only be accessible for a user with Modify permissions on the project and a Manager licence and will be visible with either the Home or the project and Stage properties selection.

The PM can fill in answers to the questions asked about the project.  As standard these are related to a portfolio management capability and feed the Project Summary data report.  These fields are controlled by the project's method template and as such may be different on the project you are viewing.  These fields can be customised and extended in Method Manager to apply to all projects of this type.

The contents of these fields, including customisations, will be shown automatically in the Project report and you can also undertake your own analysis of them in the Project Summary data report.

If you want to add additional properties/attributes to your project then use the Project Extended Properties tab within this form.  Proerties added there will exist just for this project they will be shown in reports are will be available for use in Office Export properties but will not appear in project/portfolio selection attributes.