On the left navigation bar, in the box that holds the name of your site, click "Pages"
In the top right, click "Add new page"
Fill out the title, the URL slug (the name of the url you want the page to have), and whether or not you want it added to the navigation part in your site.
Click "Add" in the top right.
Adding Content to a Page
Click the pencil icon next to the page that you would like to add content to.
On the right, find the type of content you would like to have added.
Fill out the information for the new block that has been added.