I'm new to assembly and I want to learn the language. I downloaded the NASM compiler and I'm trying to compile (assemble?) my programs with it. I'm assuming nasm.exe is the compiler. When I try to compile, it gives me errors. The code I'm trying to compile is:

.model small
.stack
.data
message db "Hello world, I'm learning Assembly !!!", "$"

.code

main proc
mov ax,seg message
mov ds,ax

mov ah,09
lea dx,message
int 21h

mov ax,4c00h
int 21h
main endp
end main

Also, I eventually want to write my own Disk Operating System, would ASM be the way to go if I want to do this?

Thanks, any help is appreciated.