First login into the admin and then click Pages—>click Add Sub Page.
Add new Sub page will appears..
Fill all the field which is mentioned below:
Select main page
Hidden Page—>after giving this click submit button in the bottom of the page.
After submitting –>see that in list of pages.
After Submitting ,it will shows in the already existing Static pages list
The added sub page—>>need to visible in front end —>click UNPUBLISH as PUBLISH.