If you plan to attend the informal Christmas party after the talk and singing, then think about bringing something tasty to eat for you and 2-3 others (but not tooo much!).
If you have the time and inclination, please try to find on the net a recipe of treats, cookies, cakes...like for Christmas celebrations in America, Great Britain or Western Europe, and make something tasty to share with others!
It might be Christmas treats like those at the links below, or some appetizers or fruits. You do not need to bring something, but if you feel you would like to, then please do.
(There will be some drinks provided. )
Try these sites for some Christmas treat ideas:cookies, cakes, etc.
http://www.joyofbaking.com/ChristmasBaking.html
http://www.thebakingpan.com/IndexPages/christmasbaking_index.html
For converting measurements, see:
http://www.joyofbaking.com/ConversionsEquivalencies.html