To sum them all up, here is a quick list of Christian festivals:

The beginning of the Year is Spring! (The Spring festivals of Jehovah)
in the first Moon, on the 14 day the Lamb is slain and prepared,
eating the Passover after sunset on the 15 the first day of unleavened bread also known as Passover, a high holy Sabbath day.
15-22 we eat only unleavened bread, the last day of the festival and a high holy Sabbath day.
In between this festival when the Seventh day Sabbath of the week comes around, the Day of first fruit dawns the next day on the first day of the week. We count 7 Sabbaths or 50 days to the Day of Weeks, another High Holy Sabbath.

7 Moon of the year begins (These are the Fall festivals of Jehovah)
When the Sliver of the moon, the new moonth of the Seventh — we celebrate the day of Trumpet, the festival of Trumpets and Atonement last 10 days in total, the first and last being High Holy days. On the 15 we celebrate the festival of Booth, first day being a High Holy sabbath day, 7 days in total and the 8 being the last great day, a high holy day of Jehovah.

Always confirm with Scripture — I'm writing from memory and still learning myself.