To add a page after the active page or spread, click the New Page button in the Pages panel or choose Layout > Pages > Add Page. The new page uses the same master as the existing active page.

To add multiple pages to the end of the document, choose File > Document Setup. In the Document Setup dialog box, specify the total number of pages for the document. InDesign adds pages after the last page or spread.

To add pages and specify the document master, choose Insert Pages from the Pages panel menu or choose Layout > Pages > Insert Pages. Choose where the pages will be added and select a master to apply.