Magento

I got a series of questions, if you guys can help me out that would be great

Im a little confused on how magento calls pages. When I go to page.xml in the layout folders. It shows by default that the structure should be a 3column layout. but when I bring up my page. its calling a 2 column right layout. How do I go about changing that.
When I go to manage pages in CMS within the admin page, it also shows a 2 column right layout. So Im just a little confused on what page.xml is for. I thougth that it managed the main layout for pages. yes I have read the design tutorial about three times, thats what I get out of it

Plus Im having issues loading the sample data. because as of right now there is nothing on the page and I cant get to the rest of the website because there is no products. So theres no way in the world I can learn what all this magento has. So I used the installer for my web hosting service to load magento but it came with no sample data. My question is how can I load it in, after I installed the product. i already tried wiping the database clean and loading the products in and adding the media file. but when i click on products, it says it cant find the pages. can any help me please. This is like my 10 forum post and so far I got 0 response.

hi!!

See that you have got yourself into a fix there - let me take this one at a time
i. On page.xml - is the default layout for all the pages - common elements like JS libraries/CSS styles are loaded using the default specifications mentioned on this file.
In all default cases, pages are rendered as 3columns as per page.xml. However this is overriden in pages like Catalog product details using

Note here that the default 3column layout is overriden for the product details page (catalog.xml layout file).

ii. I haven’t personally favoured the sample data. But I used the sample data in an older release and am not sure how it is in the new one. But am sure your problems are most probably not because of the sample data. So please wipe out everthing and re-install and try again.

and front page according to the sample data. Besides over riding the pages in the admin page, where do i over ride them programatically. The tutorial said I can go into a module such as catalog.xml and over ride it. But catalog.xml is a content block, not a structure block. Are they saying I can go into any module and over ride a layout of a page ???

to my knowledge only CMS pages like Home page, About Us etc can be controlled from Admin

In case you need to change the layout of other pages - say product details page - you can change it in
app\design\frontend\default\default\layout\catalog.xml (tag <catalog_product_view> in specific)