Since this was requested, I'll make a little "hello world" program in assembler. Note that it's designed for Nasm. Different compilers have subtle differences in syntax.

Code:
SEGMENT .data
message db "Hello world."   # our message
db 0Ah
db 0Dh   # return carriage and line feed

SEGMENT .text
mov eax,04h   # eax = 4 for system call to write to file
mov ebx,01h   # file descriptor, in this case 1 for stdout
mov ecx,message   # address of message
mov edx,0Eh   # number of bytes long
int 080h   # call linux
mov eax,0h   # system call to exit
int 080h