I got 2 monitors, but emacs can only use one, can I use both of them, so that I could split windows cross both monitors? so If I want to create 2 windows, then each monitor could show me one windows.
If I'm understanding the question, try
C-x 5 2 (the default binding for
make-frame-command) to create a new frame. You can have several frames and position them on your various monitors however you like.
C-x 5 prefix has several other commands for dealing with frames. Try
C-x 5 C-h for a list. See the Emacs manual section on Frames for more information.