Hi I have a document fora book. I wonder if you could help Mehmet to put page numbers

These sections from the "Related Article"" linked here and at the top of this discussion should provide the information you need:

Work with headers and footers

You can add or remove headers and footers, show or hide them, add content to them, and more. Learn how to work with headers and footers on Mac.

Add page numbers

If you want page numbers to appear in the same location on every page, put them in the header or the footer. You can add page numbers or page counts to your document header or footer—click into the gray text box, then click Insert > Page Number.

After you've added page numbers, you can change the starting number and numbering style:

1. In a word-processing document, click the Document button , then click Section. In a page layout document, click an empty area on the page, then click the Format button  to show the Page Layout inspector.
2. Under Page Numbering, click the Format pop-up menu to choose between numbers, roman numerals, capital letters, and lowercase letters. 
3. You can also choose whether you want numbering to continue from the previous section, or start at a specific number.
4. To place a page count into your document, click into the header or footer text box, then choose Insert > Page Count.

Regards,

Barry