An atheist's question about Christmas?

I have never had a Christmas tree before. My parents were JW's so I didn't have one when I was a kid. I have seen them in stores, but I never put one together before. What in the heck are they supposed to look like? I don't have all the packages under there like at the department store. I don't have all those round shiny things either. I just have a tree and some lights. Now what? I put some candy canes on there, but it looks kind of like, I don't know, it just well, it's white for one thing, and all the lights are blue. Okay? I confess, I don't know how to do something. How do I make this look good? Also, believe it or not, my very Catholic wife put out a nativity scene with the figures that are about five inches tall right next to my Hot Wheels. Dangit, you don't think the baby Jesus will go for a spin in my 1970 green and white Plymouth Roadrunner, do you? I don't get this Christmas display stuff. Explain it to me. Please?