how can program get command line?

The command line parameters are stored initially on stack. At the entry point of your program, the stack layout is as follows:

dword [esp] = n, count of command line arguments
dword [esp+4] = pointer to the first argument (the name of your executable)
dword [esp+4*2] = pointer to the second argument
...
dword [esp+4*n] = pointer to the last argument
dword [esp+4*n+4] = some NULL pointer
dword [esp+4*n+8] = pointer to environment variables

thank you!