Google Webmaster tools - Sitemap error

[David Rose]

I've just added Google webmaster tools to my site.

Now, when adding a sitemap I receive the next error on each page I add:
Sitemap is HTML
Your Sitemap appears to be an HTML page. Please use a supported sitemap format instead.

I guess that what I need is to create a XML Sitemap, is there some kind of a plugin that can help me do it?

Thank you

[GameFreak2009]

In the Admin Control Panel, at the bottom of the navbar there is a tab called 'XML Sitemap', what about trying that first? :D