Your Address Book shows you your contacts and their contact details. To search through your contacts, you can type their name into the search box and click Find.
Sendible allows you to filter through your contacts by using the Filter box. Here you can filter by various types of services, for example Social contacts, SMS contacts or Facebook contacts.
To compose a new message from your Address Book, click one or more checkboxes next to the recipients names and click the Compose button.
See Deleting or Editing Contacts.