To add information about a new character you should use DT_CharacterInformation. Here you can duplicate any row and put your information: name, description and images. All these things will go to his tab in glossary once this row somehow added to characters info variable of the component (see Glossary page).
In dialogue character you have an example of adding both characters and creatures:
Default value looks like this:
It works the same for creatures: you create a row in the DT_CreatureInfo and then use it to add a creature like in the picture before.
Here is an example of initializing a creature variable in BaseAI.