You've virtually done away with the left sidebar area where widgets would go, making it only 100px wide. I have to maximize my browser window on my 1440px wide laptop monitor to see your entire site. There is something messed up in your CSS that keeps a horizontal scroll bar from appearing, so most people will not even know you have a search box to the right of your main content (they won't be able to scroll to the right to see it).
1024px wide monitors: 14.6%
1280px wide monitors: 10.5%
1366px wide monitors: 23.6%
What you have to do is to put the search widget into the sidebar and then use the specific widget ID for that search widget and use position: absolute to move that widget over and to the right of your content. This is just example code and after putting the search widget into the sidebar, you will have to look at the source code on your site, find it, and get the ID for that particular widget.
You will have to adjust the left and top values as needed. I've specified "left" instead of right because your site is pinned to the left border of the browser window.