key binding doesn't work under consle mode

["kid kid" <pluskid.zju@gmail.com>]

Hello!
   I have problem using Emacs. I use some key binding defined in my
dot emacs file:

(global-set-key "\C-h" 'delete-backward-char)
(define-key global-map "\M-h" 'backward-kill-word)
(define-key global-map [C-return] 'set-mark-command)

It works perfectly in emacs, but when I run "emacs -nw",
 I can type C-h to backword delete a char, type M-h to
 backward kill a word, but I can't use C-return to set mark.
 However, I use M-x describe-function <return> set-mark-command,
it says "It is bound to C-@, <C-return>, C-SPC.". But when I
type C-return, it just start a new line. I tried in the rxvt terminal
simulator or in real console(use Alt+Ctrl+F1), it doesn't work.

And I have another problem: when in real console(I mean switched
by typing Alt+Ctrl+F1~6), I can't use Alt key. When I want to type
M-x help, I must type ESC, then release it, then type x, then help.
Why doesn't the Alt key working in real console? Is it the fault of
wrongly configured emacs or the console?

                     Thank you!
                   pluskid