I used bondo to smooth out the gaps, but I didn't have any experience with bondo or any fabrication thing... I felt it's quite hard to work with bondo and I finally lost patience after several sanding...

so I ended up with something not very nice, but it still works
the computer is now mounted in the cup holder slot right below the LCD... not the silver laptop on floor. DVD/CDRW is together with the computer. HDD and ITPS is in back of the LCD.
I will solder some wire for the VGA connection and others, so the connectors would not stick out of the dash board, then I'll find something to cover up the computer.