Hi there,
I have worked on several of these and they are tricky the first time.
Unscrew the 4 main screws and remove the stand.
Then on the bottom of the frame, there are two very small little slots. That is where you carefully pry it open. It helps to have two small scredrivers for this, both smaller thin style.
There is a thing called a spudger you can find online that is a small thin nylon stick, I have a few of them, and it helps to pry open the face.
You have to get a little tiny opening, then stick in a screwdriver, then the other side, and keep carefully moving along seperating the front face panel. It is very slow, and do not get too crazy, just be patient.
This is not the exact model, but gives you and idea of how they come apart.
http://techrepublic.com.com/2346-13636_11-156870-6.html
Good luck!