Working with div - Help

Question

Hi,

I'm an engineering student who's just started working with ASP.NET as part of a training program. The language I am to work with is Javascript, and though I do know how to work with HTML, I have never coded in Javascript before. However, as training, I've been assigned the job of debugging an ASP.NET web application project. The particular bug I am stuck on right now involves a div (division).
Description: The project is a website designed for a truck rental company. The particular page on which the 'bug' is, is called Inventory Status Grid. It's basic job is to display inventory according to the date entered by the user. On the top row of the page there are menu options: F1 for Help, F3 for Exit, F4 for Accessories, F5 for Vehicle specification, F8 to display more options, F10 for Notepad etc. 
When the user clicks the F4 menu option(or presses the key), a Vehicle Accessories div gets open in the foreground, and the background is blurred. The div has the Esc option to close it. 
The way the application should work is that when the div is open, the user should not be able to click any other menu option (or specifically, the F3, F5, F4, F8,F10 and F11 keypresses as well as clicking any other key of the keyboard should be disabled). Clicking or hitting F1 should be allowed,as it opens a Help div for the user , but no other keypress should be allowed while the div is open(except Esc of course, to close it).  How do I get about achieving this? Can someone please let me know, I do need to get this bug solved by Monday, and I confess to be quite lost right now.
Thanks.