OK. Your case label is wrong. Case only accepts either a number of a constant. So you can say case February, because February = 2, which is how you defined your enum.
Now, think about this: when you're inside your February case statement. You're printing that Feb has 28 days at the moment. How about putting your leap-year check within the case statement, and then print out either 28 or 29 depending?

QuantumPete