You add new pages to your site via the Pages manager. You can reach the pages manager in two ways:
When in the Pages manager, click the 'Add new page' link
Give the page a title. The other fields on this page will auto-complete, although you can over-ride these other fields in you like. For example, if your new page has a very long title, you may choose to give it a shorter name in the navigation menu.
The page URL is the website address for this page. Again, you can edit it.
If you are still working on a page you can leave it unpublished. Once you're ready for people to view this page you can change its status to 'published'.
You can choose from a variety of page types. Learn more about page types.
Page meta data
Learn more about meta data here. Giving each page unique and descriptive meta data will help your site's ranking in search engines.