Templates preferences
The list labeled New Document Template contains all of the available templates (files in one of the template paths); the selected one will be used for new documents you create. To select a different default new document template, just click its name in the list.
Search Paths for Templates are locations of folders on your disks which OmniGraffle checks for template files. APPWRAPPER is a special case that represents the inside of the application itself; the other paths listed by default are the various Application Support folders on your Mac and on the network. Any OmniGraffle files in these folders become available as templates. To tell OmniGraffle to check for templates in another specific location, click the plus button, then double-click the new entry to edit it. Type or paste a path to a folder on your Mac or on your network. To remove an entry from the list, select it and then click the minus button.