Any .tpl file in the active skin's folder is a page at its own address. A skin template named greendog.tpl shows at yoursite.com/greendog.
For a page without code, use Site Builder instead. See Creating a New Page.
In a cloned skin, the Templates tab has Create A New Template In This Skin:
greendog.tpl, and click Create.To give the page the site's header and footer, include them:
{jrCore_include template="header.tpl"}
<div class="container">
<h1>Green Dog</h1>
<p>Hello from greendog.tpl</p>
</div>
{jrCore_include template="footer.tpl"}The page is now at yoursite.com/greendog.
Create the .tpl file in the skin's folder on your server, for example by copying index.tpl. It's a page straight away.
To change how lists and module pages look instead, see Changing How a List Looks.