[otrs] Need help Adding to E-mail address book

I am wondering if there is a way to add e-mail addresses to the address book when answering a ticket? When you compose an answer via e-mail you'll see next to options three links: Spell Check, Address Book, and Attachments. When I click addreess book how can I add a new e-mail address so that when another agent answers a ticket they have a list of potential addresses? Also what is the search bar for? thanks marshall