<em>I'm busy</em>

<em>Nan bappa... </em>
<em>(did i say it right form?) ^^</em>

Hi Cris,

I'm busy: Bappayo or Jeo bappayo

(Nan bappa = Na neun bappa <-- which does mean 'i'm busy' but in the plain/intimate form. So unless the person you're saying it to is your age or younger, close friends with you, or you're intentionally being rude/sassy/curt like 2ne1 lol; you wouldn't say it quite like this. The "yo" on the end of verbs makes it standard polite form, not too formal, not too casual. Being a beginner myself i find it the safest form to use.)