When you visit a country, it is important that you have the necessary travel documents to enter and stay in that country. U.S. citizens do not need a visa when traveling to Canada, but citizens of many other countries are required to have such a visa. If you need a visa, you have to contact the Canadian Embassy in your country to submit a visa application. If your application is successful, the visa will be inserted in your passport and checked by Canadian immigration when you attempt to enter Canada.
Download and print out the application package from Citizenship and Immigration Canada (see Reference). Check whether nationals of your country are required to have a visa by clicking on the "Do you need a visa?" link on the website.
Read the application guide and complete the application form.
Enclose your passport, two passport photographs, the application fee -- $75 for a single entry visa, $150 for a multiple entry visa or $400 for a family -- and evidence to show that you can support yourself when in Canada, such as a bank statement or a sponsor's letter. You might also be required to attach extra supporting documentation, such as identification cards, proof of employment, a letter of invitation from relatives or friends in Canada, or a proposed itinerary. Contact your local Canadian Embassy to find out the specific requirements for your nationality.
Send or take the application package to your Canadian embassy. Processing times vary between different embassies. You might also be required to submit a medical test and attend an interview.