Creating a Document of a Non-standard (Custom) Size in Pages

Creating a document of a non-standard size (custom size) in Pages isn't straightforward: as pointed out at https://discussions.apple.com/thread/5501217, in order to create a document of a custom, non-standard size in Pages, you have to go the File menu and choose Page Setup and then in the dialog box that comes up, for the Paper Size option, you have to choose Manage Custom Sizes. Then you'll get another dialog box and it should be pretty self-explanatory what you do there to create your non-standard paper size. After you've created your custom paper size in that dialog box and pressed the OK button, you'll see that back in the Page Setup dialog box, the custom paper size you just created is listed for the Paper Size and of course you'll then want to press the OK button there and now your document in Pages should be of the size you want. To change the properties of the page (page orientation, margins, header, footer, and so on), you'll need to click the Document button in the upper-right corner of the Pages button bar at the top of the window) and then the Document button beneath that.