I want to clarify a couple of things that Alex said. The pay depends on things like what unit you're in, once you get through the training. Some units are paid more than others, and things like traffic volume come into play, there. Either way, you should be careful not to let the pay be your primary reason for getting into the job, and here's why:
I've watched some people -- some good people -- sit and work and be nothing but nervous all the time. The job is stressful (don't believe what they say on the website), but it's not the amount of stress that becomes important. It's the personality type -- yours. People handle stress in many different ways. You might have every necessary mental ability to handle this job, but if you don't deal well with stress, the job can eat you up.
As far as qualifications go, the only outright qualification, academically, is high school graduation. Other than that, you'll receive the training you need from the instructors at various levels along the road. Having a background in aviation will help, since there are several concepts you will be better prepared for than your classmates, but it isn't required. A lot of attention to your course during the studying will make a huge difference. Don't let yourself get too distracted or it can mean you falling behind and being CT'ed.
There are some other items that have to be dealt with prior to training. You must pass a Class 2 medical (Transport Canada standards which can be found at
www.tc.gc.ca, but it's a long search and a convoluted document -- basically, you have to be healthy) and there is a background security check, including fingerprinting.
Once thing I find amazing when I look around at my coworkers, all currently qualified ATCs, is the diversity of backgrounds. You could be book-smart, but fail miserably during practical portions of the training. You could struggle to pass each exam, nearly failing out, and excel during simulation. It is difficult to pick out any one trait or a group of traits that will serve you well or keep you out. The only thing to do is like Alex said: Do you own thing, seek help when you need it, and keep studying. The numbers in the past for successful training have been dismal, but it doesn't mean you don't have a chance or that your chances are slim. It just means that the job isn't for everyone and the only way to really know is to go through the training.
By and large, the job is thankless and job satisfaction comes from within. No, you don't get free air travel -- there are no real fringe benefits like that. But the pay is good, and if you have the right personality, it's the best job in the world. You had better like shiftwork, since most units across the country involve it, and many are 24/7 operations, which means night shifts, too. You can contact the Shift Manager at Moncton ACC at 506-867-7173 to ask about a tour. Good luck!