The more advanced format isn't much more difficult to create and lets you specify additional information about each URL. The protocol is described fully here (https://www.google.com/webmasters/sitemaps/docs/en/protocol.html) and is too detailed to explain here. Your finished file will look something like this, except (hopefully) with more URLs specified:

http://www.cafeid.com/
2005-01-01
monthly
0.8

http://www.cafeid.com/art-over.shtml
weekly

Your Sitemap's location dictates what URLs can be included in it. A Sitemap placed at the root level of your site can specify any URLs on that site, while a Sitemap placed at www.yoursite.com/images can not include URLs under www.yoursite.com/banners, for example.

You can take as full or as little advantage of the availability of the various additional XML tags available in this format. Each needs to include at least the specification, but need not include the other three, and all URLs in a Sitemap file must be encapsulated within the tag. We recommend using at least the tag and the flag to let the Googlebot know how often it should check your site for updated content. Be sure to change the date, and maybe even the time, specified in the tag any time you actually update your site.

One more caveat is that your URL specifications must be XML-encoded, similarly to the way they're encoded under RSS. What this means is spelled out in detail here (http://www.w3.org/TR/REC-html40/appendix/notes.html), but essentially, what you're doing is converting a URL like http://www.yoursite.com/view?widget=3&count>2 to look like this: http://www.test.org/view?widget=3&count>2 (Note the substitution for the HTML entities & and > for the "&" and ">" symbols.)