transitioning from the Uk's education system to Canada's

I'm currently in my first year of college (in the UK) but will be moving to Ontario, Canada next year towards the end of year 12. I don't really know what year/grade I will be going into and how it is different to year 13 in the UK and if there are any equivalents to A-levels there. Also what do you need to apply to a Canadian university? If anyone has any guidance, it will be very much appreciated because I'm really confused!