Bring Me The Head of... Oh Wait

This one realy made me laugh, so many "bring me his head"-quests in this game and then we come to the headless horseman who got none.

Oh lawd. The title of this achievement is pure genius.

I need someone here to tell me HOW to do this. I am level 85 and I see NOTHING in the graveyard that indicates where he is and what to do.

Walkthrough please.

Step 1: Open up your Dungeon Finder Interface
Step 2: Click dropdown arrow where you choose the type of dungeon
Step 3: Click "Headless Horseman"
Step 4: Click "Join Queue"
Step 5: Wait
Step 6: Click "Accept" when queue pops
Step 7: Begin boss encounter by right clicking pumpkin
Step 8: Kill easiest boss ever
Step 9: Profit

/walkthrough complete

NOTE: You must be within 1 level of the current maximum level to do any of the holiday bosses. Other posts saying lower levels can get the achievement are outdated since 4.2 all holiday bosses are accessed via the dungeon finder.

NOTE2: You can also no longer invite people into already-formed dungeon groups. I've tested this several times, and it's quite frustrating when tanks kill one boss then leave and you cant invite a friend to save the day =(