The Buntline Hitch is used to stabilize items, because it tightens with jerking and shaking. It cannot be tied under load, as it will jam if under a heavy load.
Find the item you're tying the knot around, and put the live end around to the back of the item.
Bring the live end around the front of the dead end.
Take the live end around the back of the dead end.
Wrap the live end back around the front of the dead end.
Once the live end is in front of the dead end start to bring the live end up.
Take the live end around the part of the dead end that is above the wrap around you made, forming an elbow.
Bring the live end under itself making sure it is above the part of the rope going in the same direction.
Congrats! You're done!