Adding documents can be done from the Settings (found in top right next to your name) > System Settings

Click on Document Settings

That will then bring you to the following screen

Click on the Green Button "Upload Documents" and the following screen will come up -

You can then drag the document into the box

Under the section "Business Cases" there is a drop down menu which has the list of various sections that the document can be added to -

Depending on where you want the document to appear, click on the corresponding section and then the document will always be attached at that point of the process.

For example, a TOBA would need to be added at Issue Policy Documents and New Business Proposal as well.