Welcome I'm Chris aka Moose
It all depends on the style controller you got. Most controllers need power, ground, and brake applied power. If you do not have a brake pedal switch that provides power when pressed then you can splice into a brake light, though it needs to be a brake light that comes on solid, not one that pulses like the style in conjunction with the lower rear turn signals. There are also some brake controllers which work off of inertia not by brake input. Having a machine shop make you a bracket near the brake pedal with a simple on off pressure switch is also an option if need be.
-----------About me and Just Answer------------
I am in my upper 30's, have a wife and 2 sons. I farm, fish, hunt, build, and coach youth soccer. I work on anything with an engine, been to many schools and classes through my 12 years with the dealership to get trained and certified. I try the best I can to share what I know and or have access to with my customers. Please consider I base my questions and answers to you, solely on the information you give me since I am not there to see, smell, hear, touch, or test. I try my best to be here everyday starting at 3pm central. Rating an answer is required. Please let me know if your not pleased prior to rating or if you cannot rate me so I can try to help a different way. God Bless and have a great day.