If you want the box on the right to be on the left, it must come first in your HTML code. Don't forget to clear your floats afterwards.
<div style="float:left; width: 200px">
This is floated left
</div>
<div style="float:left: width: 500px">
This is floated left
</div>
<footer style="clear:left">
This is footer with float clearing.
</footer>
Nancy O.