sidebar problems

I am having a problem making my sidebar float to right of my main content. I have my main content div size at 1200px. I have to smaller div’s floating to the left. They are 700px. When I float my sidebar to the right it does go to the right but stays below my last div tag. I have tried everything to make it go to the top right. of my main content div. This site is not active, I am using a test server. Any thoughts?