To create a new document:
Choose File > New Document to display the New Document dialog.
To change the page size and orientation, click the Change button to open the standard macOS Page Setup dialog. You can select a standard page size, or select/create a named custom size.
Select the number of document pages. You can add more pages later using the Page & Spread Inspector, Thumbnails window, Edit menu, or contextual menu (with no current selection).
Select the Spread Editing option (also known as facing pages) if your document design is to be based on double page spreads, in which images and text are allowed to span the page divide. Selecting Spread Editing will also provide Inside and Outside page margin settings (replacing the Left and Right margin settings). Producing a glossy magazine or brochure are typical examples of documents for which the Spread Editing option might be selected.
Set more options, if required (see below for information).
Click the Create button to create the new document.