Fixed positionning

Hi everyone,
i am new to this forum and this is my first post.

i really need help on the following please:

I want to make a fixed positioning for 2 div.

Actually what i want to achieve is that my "header" and "another box which will act as a footer" should be fixed, while the content in between scrolls.
something similar to this Demo

The following is the code for my header, and it achieves the header part. How should i proceed for the bottom part?

#header-wrap {
width: 100%;
z-index: 999;
position: fixed;
top: 0;
left: 0;
}