Custom Styling 101

I’m just learning how to work with WordPress, which I hope to incorporate into several websites. I’ve learned how to make posts, organize them into categories and create pretty permalinks. My next big obstacle is customizing my pages’ appearance and functions (php includes, JavaScript, etc.).

I would like to replace WordPress’ default home page with my site’s original home page.

You can see the current world section home page at http://www.great-depression2.com/world

I want to change it so it looks almost exactly like the page at
http://www.geosymbols.org/World/

Of course, the child pages (e.g. MySite/world/spain) may be a little different.

I’d like to do something similar with the topics home page, except that I might retain some WordPress functions, notably a list of published articles and archives.

I’d probably leave the News section (MySite/news) untouched; whatever WordPress creates, I’ll leave alone – for the most part. I do want to put some top navigation links, footers and Google AdSense on all of my pages.

Anyway, can someone tell me how to get started? How do I modify a page at MySite/world and add a different change to child pages, such as MySite/world/spain?

Thanks.