You cannot post to pages. Pages are static and sit outside the blog structure. Staff have provided help for those who want to structure their blog like a website. > http://en.support.wordpress.com/using-wordpress-to-create-a-website/
What’s critical is:
(1) a clear comprehension of the differences between pages and posts > http://en.support.wordpress.com/post-vs-page/
(2) a clear comprehension of the fact that there is only one dynamic page in a blog for posts and we cannot post to more than that one page. But we can create the appearance that we have posted to more than one page.
We organize our posts by assigning Categories to them. When we publish a post it automatically appears on the running page for posts and also on the Categories pages and Archives pages. Note: There must be one published post in each Category in order for there to be anything to display.
A custom menu allows you to display Categories with drop-downs to sub-categories in tabs along the horizontal navigation where normally only Pages tabs are displayed. If you wish you can also include Pages with drop-downs to sub-pages and custom links in your custom menu as well.
How to create a custom menu. http://en.support.wordpress.com/menus/
Troubleshooting – My menu isn’t appearing
Go to the custom menu page in the dashboard Apearance > Menus and in the “theme location” module at upper left select your custom menu from the pulldown and then click “save”.
Troubleshooting – My pages aren't appearing
Have you enabled “Automatically add new top-level pages” function and then saved the menu? If you have established a Parent page and child page “hierarchical structure” in the page attributes module and/or any “order” numbers you have assigned that conflict with the order you are creating by dropping and dragging in your custom menu change them so they are the same order as you establish in the menu. Establish consistency – problem solved.