Use relative paths for internal links
When creating links from one pages of your Drupal Gardens site to another, use paths that begin with a "/" slash, not your domain name. If you ever change your domain name within Drupal Gardens or export your site and republish it under a new URL, this kind of link still work:
<a href="/path/to/content">some text</a>
Drupal will automatically add your domain URL to this kind of path:
<a href="http://yoursite.com/path/to/content">some text</a>
Do not use full paths
If you add a custom domain to your Drupal Gardens site, or change your domain for another reason, this kind of link will no longer work:
<a href="http://yoursite.drupalgardens.com/path/to/content">some text</a>