CSS nightmare

Ok, so recently I have been dedicated all of my time into building a website that I have been planning on building for a long time. All i have to say is that CSS is driving me up the effin wall.

1st issue: I designed my layout so it would work with 1024 resolution. But then I realized that in higher resolution my website is left aligned. I have learned through w3schools studying css that margin:0 auto; centers your page, I tried that to no avail, it just start doing some really screwy stuff. My menu bar in particular. After spending hours upon hours I am near pulling my hair out.

2nd issue: Rounded corners, I would like my content element to have rounded corners. Since I am nowhere near able to code anything like that myself, I saw many sites on google that will actually generate the code for you.. great huh? No, not for me anyway, I follow instructions to the tee and still I have yet to accomplish rounded corners on my content box... again, more hair pulling after hours of frustration and trying many different methods.

I like to accomplish things on my own, not one to jump to others for help, but I really just can't take this anymore. I am providing some links to the source code, I appreciate any help you can provide.

Thanks in advance,

Noob ***, borderline suicidal over CSS, coder.

Source: http://o-megastore.com/pooponastick.zip

I use this method for all of my centered page wraps:
http://www.bluerobot.com/web/css/center1.html

and if curved corners are bugging you, you could always resort to this:
http://www.curvycorners.net/ (relies on javascript to round the corners... It's easy to use, but people can tell when you're using it because it loads kind of slow)
or
http://www.spiffycorners.com/ (recommended)

I'll take a look at that centering source,

I've tried spiffy corners, doesn't work for me.

*edit* I looked at that centering method and that is the one I tried to use, when I try to use that on any of my other elements i.e nav bar, side columns, it just screws it up. It does work on my content element though.

*edit* also to be more specific about spiffy corners, when I tried to use it to round out the corners on my content box, the only thing I could get it to do was add a rounded rectangle that appeared at the very top of the screen.. i believe i put: <div id="mycontent" class="spiffyfd"(or whatever it is)>