Are you thinking about applying to a University in Ontario? If so, www.electronicinfo.ca is the BEST place to do your research. The Ontario Universities' Application Centre is also a great resource. The OUAC 101 application can be found here.
Thinking about going to a university outside of Ontario? If so, www.myblueprint.ca is a good place to start your research, but sure to check the individual school's website for the most accurate application and admission information.