Magento Layout – Change the Size of Homepage

I’m currently using this theme (http://demo.pagayo.com/pagayotheme001/) on my website. Although this theme is great and better, comes for free I still have the complaint for with its Horizontal size. It’s too large to fit in screen. I don’t think that Customers actually like scrolling the page searching for things they want. I want the website to fit in the page. Being an amateur in PHP, I really don’t have any idea how can do it. I know if the length is changed then I’ll have to change the size of images too, but isn’t this possible that the images get resized automatically? Anyways, if that’s too hard to incorporate then anyone can please help me in at least making my website page fit in the screen horizontally? I’m good with vertical size, that is scrollable and the customers wouldn’t mind in scrolling through width. So, in short I want help in following:

1) Making the website fit in customer’s screen as per their browsers setting & resolution, automatically.
IF automatic accommodation of page is not possible, then

2) Help with the code to at least make the website fit in full, horizontally so that customers do not have to scroll for horizontal view. If you’re gonna suggest me a code change then it’s my folded hand request to please provide the code as well and the directory path where I should make the change. I’m a child in the world of coding and Magento so I don’t know anything. All I know is, I have to complete my website anyhow!
Please help me out and I’ll buy you a beer 🙂

Well I read somewhere that I need to make amendments in styles.css file. I opened it and seconds after I lying on the floor knocking my head. There's hell lot of codes which is almost an alien language for an amateur like me. Here is the Styles.css file of my homepage. Can anyone please tell what exactly should I modify? http://www.dirtrades.com/styles.zip