In much the same way that you can add a Tag to a document or transcript, you can also add a document or transcript to a Character.
From the Documents tab, navigate to the document or transcript you want to add and right click on the row to bring up the options. Select Add to Character.
Next, type in the name of the character you wish to add the document to and click on Apply.
You will see the Characters icon appear on the row for the document or transcript to indicate that it has been added to a character.
When you next go to the Characters tab and click on the character you will be able to view the linked material via the Documents and Transcripts sub-sections. Each entry acts as a link which will open the relevant document or Transcript when you click on the row.