Are you looking for a template tutorial for Joomla 1.5 then why not visit xtremeopensource who have created a step by step template tutorial for joomla 1.5 which guides you through creating a new theme from scratch plus the tutorial includes the essential php elements you need to include in your new design. Visit xtremeopensource for more information.

Also if you want a CSS guide for Joomla then try the following both sites are very useful to understand the specific CSS classes for Joomla.

Joomlaos Visual CSS guide its a little out dated but very useful.

Joomla-css-default-classes - Lists the css classes for Joomla.