I am trying to accomplish this:
But I am having trouble getting the two middle divs to
Here, I made a duplicate of your picture: jsbin.com/ipexep/3 (click "edit in jsbin" at the top-right to view and edit the source)
I for the height of the top and bottom sections, I took the height for them that you put in the picture.
Note: I did it by making every section absolutely positioned and setting their top, bottom, left, or right attributes accordingly.
Also, notice that my method will match every screen size. I have streched it in every area you didn't specify a dimension. (except the header and footer needed a height dimension so I guessed since you didn't specify)