あなたの国のクリスマスパーティーについて教えてください。って英語でなんて言うの？

When asking someone about how their countries celebrate Christmas, one can say something like " How does your country celebrate Christmas?" or "tell me what your Christmas parties are like back home?". These are both ways to ask someone how their country/hometown may celebrate Christmas that may be different to yours.

"Please, tell me what Christmas Parties are like in your country."
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It is always polite to include please in your request.
"Are like" This means you want to know what people do, what they eat, how they decorate, etc.
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You could also say,
"Tell me how you celebrate Christmas where you live!"
Celebrate is referring to the activities, and traditions you do at Christmas time.
Where you live - Your home country, where you are living currently, etc.

The word "like" in this sentence is asking for a description. Your listener will be able to note this and then give a description of Christmas parties in their country. I hope that this helps. :)

When talking about the country someone is from then you can say 'your country' or 'where you come from'
'please tell me' is asking them to tell you information' although you can also ask 'what are Christmas parties like'

To ask someone from another country about Christmas parties there, you can ask "What are Christmas parties like in your country?"

To someone from a different country, you want to ask them what Christmas parties are like in their country. A couple of suggestions appear above.