I just happen to notice, that I don't find a complete guide in just one thread (and the ones I found are from 2016/2015).
Many ppl on my guild (Lazy Lizards) ask about a guide too, so I did one and decided to share it with the whole community.

Christmas Event oRO 2018
First Step:
Go to one of the Event Usher NPC and let them warp you to Lutie:

They are also in Prontera, Geffen, Alberta…and I bet in other Cities too.
Second Step:
Go into the house which should be directly on the destination you got warped to with the the Usher Event.

Third Step – Start 1. Quest:
-Requirements:
1 Gift Box (unwraped)
1 Wrapping Lace
1 Wrapping Paper
- Inside the house on the right side are 3 Kafras, you have to talk first with Jasmine and then with Blossom.
You can ignore the one in the middle – she will warp you back to prontera if you want to.

-Blossom will ask you to wrap your gift and you will choose yes. Remember the colour of your gift.
-Then go and talk to Curly Sue (she is in the same room) and let your Gift Box be named…first you have to choose the colour of the gift box and in the text field you will type your own charakters name.

-Talk to her again! Now you will find another option which is „Cheer her up“ – choose it and give her your named gift box.
She will be happy and give you one of three random Headgears.
One of them is the Antonio’s Santa Hat (the best one you can get here), the others are Santa Hat and Santa Beard...You also get some other stuff

End of Quest 1.