teen holiday party-like gossip girl?

im a teen girl having a holiday (Christmas) party at my home this december. its just about 11 girls, and i want it to be formal and fancy. Its going to be a secret santa (Every one will get a person that they r going to spend $25 on a gift for) /dessert soiree. (Everyone will bring their favorite holiday treat. i want it to be really formal and fancy, but for not a lot of money and work. i was also thinking a color scheme...maybe like gold and silver.. or maybe more wintery like blue and silver..but also i was making invitations and they were like a maroon color..so maybe gold and maroon...or maroon gold and silver?? lol idk. help! Im only going to be supplying the beverages, because everyone will bring dessert. so does anyone have any suggestions??? for the drinks should i jsut have hot chocolote, milk, and water...or maybe sparking water? but does that cost a lot? or any other food/ drink ideas. decorations?? remember i want it to be formal..kind off like a gossip girl party (Tv show) thanks!
i dont mean c olor scheme for people to wear...i mean for decorations..and invites and stuff