Note carefully the structure; siteMapNodes with children such as ~/Customer.aspx are not self-closing - they have a separate close tag after the children. Child nodes like ~/Wishlist.aspx are self-closing (they have a / before the closing of the tag).
The $resources refer to language strings (see @15.2. Language strings). If your site only uses a single language, you can add links that have hardcoded text instead of references to language strings, for example:
<siteMapNode url="~/MyPage.aspx" title="MyPageTitle" description="Title of My Page" />