You do not need a visitor or tourist visa for Canada if you have a green card. You will need to have all of your paperwork up to date and in order, however. When you arrive at the Canadian border, be prepared to prove that you are a permanent resident of the U.S. by bringing along your green card and passport.
If you would like to study in Canada, you must go through the general student visa application process. You are required to fill out an application, which you can do online through the Citizenship and Immigration Canada website; submit an acceptance letter from a Canadian education institution; submit a passport, two recent passport photos and proof of permanent residency in the U.S. (a notarized copy of your green card); and submit proof of ability to finance your studies.
If you plan to work temporarily in Canada, you may or may not need to apply for a work permit. The Citizenship and Immigration Canada website has a list of professions that do not require work permits, including athletes, performing artists, public speakers, conference organizers, reporters and emergency workers. Likewise, live-in caregivers, information technology professionals and business people are in special categories with separate requirements. If you do not fall into any of the categories listed, you must have a job offer from a Canadian employer and written permission for the employer to employ a foreign worker from Human Resources and Skills Development Canada. Submit those documents, an application form, a police background check, evidence of financial stability and a doctor's report to a Canadian visa office. You will most likely have an interview with a visa officer in which you will be asked to prove that you will leave Canada when the temporary work visa ends.
