Most post-secondary institutions require a portfolio of artwork, with a minimum of 10 original pieces, showing a diversity of work.
NSCAD (Nova Scotia College of Art and Design) has an excellent, clear overview and helpful tips for how to put your portfolio together. The details are specific to their admission requirements, but the general information applies everywhere!
Here are some links to post-secondary art departments and their admissions requirements (links current as of February 2019). This is not a conclusive list! Most colleges and universities offer courses in fine arts, and we encourage you to research all of your options, wherever you may be interested in going.
Camosun College (note: no portfolio required)