The solution is in the code and you haven't posted it here so it won't be possible to help you.
Can you provide a link to your test site so that somebody can have a look at it and advice you further.
What people normally do is to copy the code to a blank document and then upload it to a web server and the link to that test page is posted here.
If you can't do this then the second best option is to post your code to these forums or to pastebin. If you post your code to paste bin then you also need to post a link here for us to have a look at it.
Paste bin is a free service for everybody to use it without creating an account.
Here is my html/css. http://pastebin.com/bvWn1nWH
OK got it. i have noticed that the mathematics of your dimensions needs to be changed slightly and also you need to introduce floats. for example, this CSS will put the sidebar where it should be but your screen is too wide so please change it:
Hope this helps but post back for further clarification.
Google labs - Browser Size
A width under 1000px will work for most average laptops & desktops. 1900+ is too wide for average users.
Also, don't use the height property. You don't need it because height is always determined by content; not explicit height values.
Do you mean change the width of the container div? If so to what size?
Use this code as your starting point and this can be improved upon as you go along:
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<style type="text/css" media="all">
margin: 0 auto;
Hope this helps.