My website was created in joomla 1.5. I want to edit my website pages header tags. Specifically the <head> area. How can I do that?
You add the <head> tags yourself in your template and can add any content you wish between those tags. In most CMS's you have complete control in what appears between the head tags. With Joomla you are required to add <jdoc:include type="head" /> however. The content of that tag is automatically filled by Joomla such as meta data (title, description, etc.).
You can edit the global meta data in the control panel Site > Global Configuration. Also on each article you create you can click on the side menu to edit the meta data for that particular article.
However, there are some things you cannot easily change. Such as in that joomla tag <jdoc:include type="head" /> it also loads MooTools for instance. Which means if you wish to load Mootools at the foot of the page your out of luck. You could manually edit the tag in /libraries/joomla/document/html/html.php however whatever changes you make there may be overwritten every time you update the system. So you do not want to do that.