How can i have a div stuck on the left side of the page no matter how much i scroll horizontally?

Programmer Question

This is kind of difficult to explain so ill link to a page that has the effect i need;

http://wpaoli.building58.com/wp-content/uploads/2009/08/feedback-panel.html

The feedback thing on the left side is what im trying to implement on my side,
instead of feedback im going to use it as a navigation menu that shows up when clicked on.

the things above is what i have right now.

my problem is when i scroll to the right ( my page is around 6000px wide )
i want it to stay on the left side,
is there a way to pull this off?

(this is to much for my brain to handle)..thanks!

Find the answer here