Generally speaking, you must meet the following requirements for a study permit:
1. You have enough money to pay your tuition, textbooks, flights between your country of residence and Canada, and living expenses,
2. The school you are going to attend is a Designated Learning Institution (DLI),
3. You have received a valid letter of admission from the school,
4. You are admissible to Canada (i.e., criminal background, health, etc.), and
5. You meet other country-specific requirements.
The validity of a study permit does not always cover the length of your study. In some cases, you may need to apply to extend your study permit. Remember, you shall maintain a valid status while in Canada at all times.