What is a shadow evocation
During evocations we need some vessel for the spirit through which the spirit will manifest. It can be a smoke, black mirror, fog, water, or light. During shadow evocations you use your own shadow as the vessel for the entity to appear through.
To set up the operation you need a very dark room. Sit on the floor and put a big candle with strong flame behind your back, far enough so you won't burn yourself, it is actually not a good idea to have the candle too close, because you need to have a good sharp shadow projected on the wall in the front of you. Oh, yes, you should be facing a wall if you didn't figure this out already.
The candle should be the only lightsource in the room so there is only one sharp shadow without any disturbances.
The format of the ritual is as always, just for the incantation you are sitting on the floor and you passively observe your shadow on the wall, repeat the incantation a couple of times and then you can also sit a couple of minutes in silence before repeating again.
During the operation the shadow should start forming its own shape and "thickness", it should become plastic and start moving on its own as the spirit enters it as its vessel for manifestation.
Continue with the ritual as you are used to.