To help answer the OP's question, here are a few very brief reasons why Jehovah's Witnesses don't celebrate "holidays", including the scriptures in the Bible where the info is located:
Christmas and Easter: Jesus was not born on December 25. He was born about October 1, a time of year when shepherds kept their flocks out-of-doors at night. (Luke 2:8-12) Jesus never commanded Christians to celebrate his birth. Rather, he told his disciples to memorialize, or remember, his death. (Luke 22:19,*20) Christmas and its customs*come from ancient false religions. The same is true of Easter customs, such as the use of eggs and rabbits. The early Christians did not celebrate Christmas or Easter, nor do true Christians today.
Birthdays: The only two birthday celebrations spoken of in the Bible were held by persons who did not worship Jehovah God. (Genesis 40:20-22; Mark 6:21, 22, 24-27) The early Christians did not celebrate birthdays. The custom of celebrating birthdays comes from ancient false religions. True Christians give gifts and have good times together at other times during the year.