re: C# Help. I always have dumb face on.

This is just translating the requirements he gave you into syntax. Once you get more familiar with the syntax you will start to see it form as you read the requirements.

(year % 4 == 0) means that the year is divisible by 4. If anything but 0 came back it means that there is a remainder and it isn't divisible.

For the centennial we check year % 100 and then year % 400.

This mean that year is divisible by 4 and not a centennial.
(year % 4 == 0 && year % 100 != 0)

This means that year is divisible by 4 and is divisible by 400.
(year % 4 == 0 && year % 400 == 0)

So we say if either of those statements is true, then the month will have 29 days.

if((year % 4 == 0 && year % 100 != 0) || (year % 4 == 0 && year % 400 == 0))