Dear (name-имя друга
Thanks for your letter.It's nice to get news about you and your family.How are you?I hope all is going well.
As for your New Year Party, I'm sorry, but I can't go to you. My parents and I are gonig to our relatives. It's put tradition to meet with them every New Year. I think,you should understand me.
Well, I must finish my letter. It's time to go to bed.
Love,(your name-твое имя)