Set Number of Pages: by entering the desired outcome (you can always add pages later).Set the Orientation: to Tall (Portrait) or Wide (Landscape).If you are making a poster, be sure to type in the desired dimensions, rather than planning to try to print a letter sized document on a large scale printer. Select a standard page size from the Page Size: pulldown menu – the dimensions will appear automatically in the dimensions boxes - or choose your own by typing in the Width: and Height: boxes.To start a new document, go to the File menu, choose New, and then select Document… In the New Document dialog box, If you are using InDesign for a poster, be sure to put in the desired print dimensions. In the Ruler Units section, change the Horizontal and Vertical pulldown menus to your preference. You can change that to inches by going to the Edit menu, then Preferences, and then choose Units & Increments (on the Mac go to the InDesign menu, choose Preferences, and then Units & Increments to change to another unit). InDesign defaults to picas as the unit of measurement.

Adobe indesign