How do I use Attachments for Models?

How do I use Attachments for Models?

Is there a program or tutorial I could read to learn how to use attachments? Like for instance: adding a Mace or Shield.

There already were 3 topics with this question, and everytime I say:

Trigger Editor:

Special Effect On Unit
Attachments are: hand(left, right) chest(left, right) foot(left, right) head, overhead, origin

Object Editor:

Make a custom ability based on Sphere (from the blood mage or avatar of vengeance)