Scroll to the bottom of the page. Just below the Create a New Story link, you'll see a Pike button. Click on it. A page opens asking the title of your story. Enter a title and click on Create.
Pike comes to the front and a new empty window appears.
Type into it. Choose Save from the File menu. Choose View in Browser from the File menu, reloading the page if necessary. You should see your changes. Write the story as you normally would, periodically saving.