How to disassemble Vostro V131?

Hi!

I have laptop Vostro V131 on my desk. I installed windows 7 pro 64 bit on it. Installed all drivers too. Now the problem is that the left side of the laptop there are 2 USB port, 1 VGA port & 1 Ethernet port are not working. It is also not showing on BIOS too. Now I am trying to check on motherboard. But somehow I can not figure it out how to disassemble this laptop. I open the screw of the back side. I remove the hard disk and ram. I remove the keyboard too. and Remove all the screws from the still plate too, which is available under the key board too. Now I don't understand how to remove that steel plate. I don't want the damage the mother board. So if any body had the video on it and if they can forward the link of it. I really appreciated for that.

Thanks in advance.