Unlike blog posts, which you are constantly writing and updating with new information, pages tend to be more static content on your site. However, after a page is created and published, you are always able to come back to make changes to that page.
Oftentimes, pages can be found in the main navigation of your site- you probably notice a big colored bar running beneath your header image and home search box on your home page. You can also link to pages from widgets or stack them up by creating drop down menus.
Here's a quick video on how to add a new page and edit existing pages: