Someone who is participating in the SS will contact you and ask you to ask their recipient what they like or don't like, and what their dog likes or dislikes.
You then come onto this forum to ask that question without giving away the identity of the SS.
While it is not required, it seems tradition has it done in the form of a poem. But many are just not poets, so you don't have to do it that way.
Here's a quick cheesy example:
Topaz and Mary, I've come your way,
As Santa asked me on this special day
To ask does Mary like chocolate and Topaz chicken
I need to know as this plot thickens....
Ok, get the idea?