Keep in mind that you can't form a kong from a melded triplet and a discard, because you already have a discard in the set.
Step3
Conceal a kong to keep the tiles available to complete sets of three. But remember that if someone else completes a hand while you are holding it, it will only count as a pung (three of a kind).
Step4
Show a kong by laying the four tiles side-by-side with the two inside tiles face up and the two outside tiles face down.