Hello, so I have this .asm file that I wrote earlier, I would like to convert it to a shellcode, may I ask how do I do that? in FASM?

EDIT:
sorry I'm a fool, shellcodes is not what I want, I can easily take that out from Immunity debugger but another question please what is it in a code that produces "null-byte" and what technique (some uses "xor") is used to avoid them

EDIT2:
So I think before I could answer all of those on the top I think I need to know first what part (I don't know what to call these: "mov" "xor" etc..)? so May I ask if there some full reference where I could find parts of a FASM code is producing null-bytes?