Before you can add anything to your CloudSite website you will need to be logged into your website editor.
For help logging in please follow this guide to Getting Started with CloudSite / FreeSite
To add a new page to your CloudSite select Pages in the left hand column.
In the Pages options select Add Page
Now select the type of page you want. If the type you want is not listed you can select default.
Enter a Page title and click Add page
You will see that you new page has been added to the page list on the left. To start editing your new page simply select it on the left