You can add more pages to your project by clicking on the pages icon in left side panel:
Click on create page to add a new page, you will be asked to name your page and to enter the slug. The slug will be the extension of the URL of where your page can be found after you have published it.
After you have made several pages you can click on the pages icon again to edit every individual page. Click on "MODIFY" to edit the slug and page name. Click on "SELECT PAGE" to start editing the page.
Now that you have more pages in your project you can start building your website. You can do that by adding menu's to your header, read here