how do I change the landing page to a different website altogether?
Do you mean the style of your site? If you mean that, you can go up to the settings bar and click on Styles. Then click on Change Style, and there should be a wide variety of website styles to choose from. You can even find them in categories like Premium Styles, or Free styles. When you click on one you like, there will be a preview of what your site will look like and if you don't like it, you can go back, and if you do, click on a next button. Behold, your new site's style! Is this what you meant?