The square will disappear then one letter will start to appear, write that down. That letter will disappear and another will take its place, write that down. Continue until the letters stop appearing. What you will have written down is the name of a spirit who inhabits that square.
Start the whole process over. Continue the process until the letters stop appearing altogether and you will have the names of several spirits who can aid you in your task. Then you can conjure those spirits specifically with the square as their gateway.