I changed the URL Segment of my custom page to 'home' under the 'metadata' tab, and it is now the home page that appears if there is nothing in the URL except the domain name (http://mysite.com), which is what I want.
In the Navigation menu, the link to the page I am using for my home page simply points to http://mysite.com. If I am at a page like http://mysite.com/about, clicking on that link to http://mysite.com does nothing.
How does one force Silverstripe to return to the home page via an unmodified URL like http://mysite.com?