Perhaps I should start with the Sabbath because it is the first mentioned; but I will save it for last.
Lev 23:5
5 In the fourteenth day of the first month at even is the Lord's passover.
KJV
On Passover I remember the Lord's suffering and death on my behalf.
Lev 23:6-8
6 And on the fifteenth day of the same month is the feast of unleavened bread unto the Lord: seven days ye must eat unleavened bread.
7 In the first day ye shall have an holy convocation: ye shall do no servile work therein.
8 But ye shall offer an offering made by fire unto the Lord seven days: in the seventh day is an holy convocation: ye shall do no servile work therein.
KJV
On Abib 15 I remember the time Jesus spent in the tomb. He died that I might have life.
Lev 23:10-11
10 Speak unto the children of Israel, and say unto them, When ye be come into the land which I give unto you, and shall reap the harvest thereof, then ye shall bring a sheaf of the firstfruits of your harvest unto the priest:
11 And he shall wave the sheaf before the Lord, to be accepted for you: on the morrow after the sabbath the priest shall wave it.
KJV
On the Sunday following Passover (Firstfruits) I celebrate Resurrection Sunday Jesus Lives.
Lev 23:15-16
15 And ye shall count unto you from the morrow after the sabbath, from the day that ye brought the sheaf of the wave offering; seven sabbaths shall be complete:
16 Even unto the morrow after the seventh sabbath shall ye number fifty days; and ye shall offer a new meat offering unto the Lord.
KJV
On the second Sunday of Sivan I celebrate Shavout (Feast of Weeks) Pentecost The indwelling Holy Spirit and the birth of the Church.
Lev 23:24-26
24 Speak unto the children of Israel, saying, In the seventh month, in the first day of the month, shall ye have a sabbath, a memorial of blowing of trumpets, an holy convocation.
25 Ye shall do no servile work therein: but ye shall offer an offering made by fire unto the Lord.
26 And the Lord spake unto Moses, saying,
KJV
On the First day of Ethanim I celebrate the promise of the Rapture when the Church will be taken to be with the Lord. I don't necessarily believe it will happen on that date.
Lev 23:27-32
27 Also on the tenth day of this seventh month there shall be a day of atonement: it shall be an holy convocation unto you; and ye shall afflict your souls, and offer an offering made by fire unto the Lord.
28 And ye shall do no work in that same day: for it is a day of atonement, to make an atonement for you before the Lord your God.
29 For whatsoever soul it be that shall not be afflicted in that same day, he shall be cut off from among his people.
30 And whatsoever soul it be that doeth any work in that same day, the same soul will I destroy from among his people.
31 Ye shall do no manner of work: it shall be a statute for ever throughout your generations in all your dwellings.
32 It shall be unto you a sabbath of rest, and ye shall afflict your souls: in the ninth day of the month at even, from even unto even, shall ye celebrate your sabbath.
KJV
On the 10th day of Ethanim I observe Yom Kippur the Day of Atonement. I try to remember that every Sin I commit in my daily life, the Lord had to suffer for. I also remember that I don't want to add to His pain. I do not keep a complete fast because I am diabetic.
Lev 23:34-36
34 Speak unto the children of Israel, saying, The fifteenth day of this seventh month shall be the feast of tabernacles for seven days unto the Lord.
35 On the first day shall be an holy convocation: ye shall do no servile work therein.
36 Seven days ye shall offer an offering made by fire unto the Lord: on the eighth day shall be an holy convocation unto you; and ye shall offer an offering made by fire unto the Lord: it is a solemn assembly; and ye shall do no servile work therein.
KJV
On the 15th of Ethanim I celebrate the Lord's birth and the promise of His return to reign over this world.
I use the pre-exilic names of the months because the post exilic names name Babylonian idols.
I call the first day of Ethanim 'Yom Teruah' Day of Trumpets rather than Rosh Ha Shanah because God named Abib the First month.
I observe the seventh day Sabbath to remember the rest we have in Jesus frees us from trying to please God in our own efforts.
I church with fellow believers on Sunday following the example of the early Church.