it dosen't work in my computer , a macbook connect to a Pcbook ...
2 laptops? Nope.
"a macbook connect to a Pcbook"
The second laptop's videocard most certainly doesn't have a "video-in" port.
The other posters probably thought the "second PC" was a desktop with a full monitor. In that case this is very easy to do. But as far as I know it would take some real wizardry to use a laptop's monitor as a display for a different computer.