Now that you have your custom page, you'll probably want to make it more accessible.  To do that, let's add a link to the Quick Launch.  Now, we talked about how to do this from the web interface before, today we're going to make the change from within SharePoint Designer.  With the site open, select Navigation from the Site menu:

and you should see a tree view of the site's navigation:

To add a link to to the Quick Launch, select our custom page and drag it under the Quick Launch tree node:

Then rename the tree node:

Now the Quick Launch has a link for our new page: