Where are you from? Based on your questions, and the fact that you're posting at around 5:30 in the morning, I'm guessing that you're not from the US.
When are the Finals in 12th grade? what month?
Depends on the school. Most likely in June.
when is spring break? March or April?
Depends on the school. Most often in March.
and a basketball question: when does the championship game for basketball take place?
Depends on the athletic conference to which the school belongs. Most likely in March.