Dog barking up the technology tree

Learning how to construct a website using tools to
allow dynamic content creation is beyond my grasp. I
need help.

Specifically, I am searching for that kind soul who'll
point me in the right path. Books, tutorials, how-to-
bang-my-head-against-the-wall instructions, that sort of
thing.

This is what I know: XHTML, some basic XML, and
CSS. I understanding concepts of programming from ye
old books on basic and pascal.

This is what I WANT to know: how to build a site using
open source software (i.e. free) that allows me to
provide dynamic content. This dynamic content would
include trivial things such as reporting the weather for a
zip code I specify to not-so-trivial things such as
allowing a user to change the stylesheet of my site so
that they could specify font, font-size, background color,
among other attributes through an interface form. I'm
also interested in understanding more about using
databases to construct content for webpages.

I amwilling to learn, even if what I'm asking requires
extensive training, I am completely clueless as to where
I need to begin and am dying for a kick-start.

Technologies that I find fascinating and seem (to me)
useful in implementing what I'dlike to do are PHP/
mySQL, SOAP, and Perl.

My operating system is Mac OS 10.2. I have webspace
that does not allow a command-line interface
connection (as far as I know). Is this needed?

Please help.