how to update the content automaticlly?

Hello, how do i  update the content automaticlly? the page number in my doc content is alway "1",like this:

       TITLE1......................1

       TITLE2.......................1

       TITLE3..................... 1

I want the content like this:

    TITLE1......................1

   TITLE2.......................2

   TITLE3..................... 3