Can someone help me with web design Question?

Firefox, safari, and opera all read my programming perfectly but IE was not happening. I made some changes but now IE looks good and the rest are horrible. Can anyone help me with this? The main content div is protruding over the header. The problem before was that the main content div was too low with a 200px top margin. With this 200px margin I was able to get it looking good in every browser but IE. IE shows the main content starting halfway down the page. I took the margin down to 0px and it looks good in IE but no good in the rest. I feel like there is a simple fix but don’t know what to do. Been doing this about a month now so my knowledge is not so good. Thanks for the time.