Now we have a completely custom page but what we really want is a page that matches the look and feel for our site as defined by the Master Page.  To accomplish this, open the page in SharePoint Designer and choose "Attach Master Page" from the Format --> Master Page menu:

Select the default Master Page and press OK:

You will then receive a prompt that asks you to match content regions to the Master Page.  This is because our custom page has content defined in the body of the HTML.  Because Content Pages do not have a body tag you need to specify which Content Placeholder you would like to move your custom content into.  SharePoint Designer is nice enough to configure a default mapping that will work just fine so you can press OK:

Now your page looks much more like a SharePoint page.

Even better, now you can browse to the page and interact with it using the out of the box actions menu: