Answer:
They made a special program that makes any picture of a person or an object a Lego mini figure or sculpture and then after they use digital animation to make the characters to move or interact and then they interpret that into the video game or animated film. :) If you mean making the sets first they have to get a contract with dc comics and then with the same program listed above they design the custom pieces and mini figs then they get a employee that has the job of building design something that has to do with batman or whatever.:)