Job in london ontario

I am new to Canada, London ontario specifically. I am looking for a part time job for when I have free time and I finish all my HW. Is their any job that doesn't have minimum hours required? meaning I can go and work whenever I want for as long as I want? Or is there a minimum time required? Also, how do I apply to jobs? Do I go to places and ask them or online or what should I do? Any recommendations on what job to apply for? I don't care what I work. But I want something with flexible times because my main goal is school and my grades. And then the job in my free time. Thank you :)

Basic rule of work - there is always a schedule. Otherwise no one would know when to work and the employer would never know if there would be enough employees to cover shifts. There are laws the control hours, after a certain number, employers have to pay overtime. Most employers don't want this so they regulate the hours. 

You don't make it clear as to whether you are a citizen or on a student visa. If you are on a visa, you are very restricted in what work you can have. Most visas state clearly you cannot work off campus. If you are a citzen (or landed immigrant) you can work anywhere. 

You will be limited in the work you are offered. Employers keep schedules and aren't interested in people who only want to show up when they have free time. You won't get any job that way. Don't say this in an interview... just don't... your resume will end up in a garbage can. Figure out how much time you can give to a job and what your schedule is. You will likely be looking at night shifts or weekends. But seriously, as someone who has had to hire in the past, any candidate that made it clear they were only available in "free time" was never, ever considered. I couldn't be bothered trying to juggle the work schedule to suit them. Most employers will think pretty much the same thing. So, figure out how many hours you can do, figure out what days you can guarantee (this is crucial), write a resume up and then see what is available in your area.