The word holiday is simply a mash of the two words: holy day.
To see what days God/YHWH called holy in the Torah/Old Testament see your Bible concordance or do a search if you have a computer version of the Bible with study helps. E-sword is what I use and like. It's free yet they depend on donations to stay afloat so be generous. There are some free and not-so-free additions to the downloads for it. The only thing I have paid for other than my donation was a Bible version. You can get maps, dictionaries, reference guides, Bible versions, and the strongly recommended, Strong's Concordance. It gives an easy way to see the definition of every word in the Bible according to the original texts. It's invaluable in clarifying disputes and confusion. A little bunny trail there.
Okay, back to the subject at hand. As an evangelical Christian, I believe that we are not expected to follow the rote of the Torah/Old Testament (the Torah/Pentatuch is the first five books of the Old Testament). I will write another post to explain why and I understand and respect that there are many that disagree. That's okay. As told in the New Testament, Jesus Christ, God's only Son, didn't require us to celebrate any holy days. He told us to "do this in remembrance of Me" (Luke 22:19) regarding what we call Communion--which is our time of reflection of His sinless body and blood given on our behalf to die on the cross for the sins of mankind. He also told us to follow His commands, which He said are wrapped up in this:
Owe no one anything except to love one another, for he who loves another has fulfilled the law. For the commandments, " . . . are all summed up in this saying, namely, "YOU SHALL LOVE YOUR NEIGHBOR AS YOURSELF." Love does no harm to a neighbor; therefore love is the fulfillment of the law.
Romans 13:8-10 NKJV
For I delivered to you first of all that which I also received: that Christ died for our sins according to the Scriptures, and that He was buried, and that He rose again the third day according to the Scriptures,
(1Corinthians 15:3-4 NKJV)
He followed all the Judaic/OT laws including Passover, but it was prophesied that He would fulfill all of them. In fact He is the emodiment of them since they paint a picture of His character as God and Creator. These rituals were explicit and were stated as representations of things in Heaven. They were also representations and annual reminders of the spotless sacrificial Lamb, His redemption through His death on the cross, and His diety. The annual reminder made sure that these truths were engrained in each person and passed down through all generations. They were celebrations since God/YHWH loves a party and the story that is being foretold and is unfolding is a gigantic, wonderful one and is what this life is all about! He planned it all before He made it all.
In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things were made through Him, and without Him nothing was made that was made.
John 1:1-3 NKJV
So celebrate! I look forward to the chocolate eggs, myself.