You may be allowed to take a program that is less than 6 months, and does not lead to degree or diploma without a Study Permit. Any study program longer than 6 months would require you to apply for a Study Permit, which is separate from a Temporary Resident Visa.
Usually people who are not Canadian citizens or Permanent Residents of Canada would require a TRV, unless they are from a visa exempt country. In order for you to gain entry into Canada with a TRV, you need to satisfy the officer of the fact that you are here on a temporary bases.
There is a list of documentation you could provide in order to make your application stronger, and increase your chances to enter Canada. A TRV only allows you to visit Canada for a temporary basis. Visitors who enter Canada with a TRV are usually restricted in the length of their stay, which is a maximum up to 6 months.
On the other hand, if you apply for a Study Permit, you may still require a TRV, but the length of your stay is extended according to the study program you are enrolled in. One of the main requirements for applying for a Study Permit is a letter of acceptance from a Designated Learning Institution (DLI). You may be required to prove that you will be leaving at the end of your study programs.