5) When you open a new application:
5.1) You will notice that the portal is the same for all flavours of applications. At the top of the page, you will have the form upload section. There you will see a variety of boxes to upload different forms for different applications. Just upload what makes sense for your application.
5.2) In a second section, you will have some more boxes to upload extra documents (like birth/marriage certificates, letters, photos, etc).
5.3) At the bottom of the page (last section), you can upload payment proof of taxes.