I am going to assume that the reaction occurs in water since that is the easiest procedure (let me know if I am not supposed to make this assumption).
1) get 2 beakers, the chemicals for the reaction, DI water, and the catalyst.
2) equal volumes and amounts of the water was placed into the 2 beakers.
3) some of the catalyst was added to beaker the second beaker.
3) equal amounts of the chemicals for the reaction was placed into the 2 beakers.
4) the two reactions were compared to see how the un-catalyzed reaction in beaker 1 was effected by the introduction of a catalyst in beaker 2.
I hope this helps. Let me know in the comments if anything was unclear.