Super bowl games at home

Todd invited Katie to his home and play some Superbowl games together. Below is part of their conversation:

....

Todd: Just a little bit of money.

Katie: So it's okay.

Todd: Just to have fun. Yeah. So, and then, once I find out what teams are in the finals then I'll tell you about the colors. And it's usually best that you choose one team that you're going to support.

Katie: Okay.

.....

I have no idea about what "Colors" they refer to and how to play the game. Please help.

LCChang