I'm not sure as I haven't actually read the story yet. But usually in a lottery story, there could be the lottery winner as a main character, and perhaps the people who run the lottery.
Tessie Hutchinson is an important character. She is the one who 'wins' the lottery and becomes the victim of the brutal tradition. Old Man Warner is also important as he represents the old - guard who firmly believes in keeping the lottery tradition alive.
One of the main themes is the danger of blindly following traditions. In the story, the lottery is a long - held tradition that the villagers participate in without really thinking about its brutality. Another theme could be the idea of scapegoating. The person who 'wins' the lottery is made to bear the brunt of the community's unexamined violence.
The lottery in the story works in a very primitive and cruel way. Everyone participates, and the one whose name is drawn is chosen as the victim with no clear reason or logic behind it. It seems to be a blindly followed ritual without any real purpose.
To be honest, I can't recall who wins the lottery precisely in that short story. It's a story that keeps you guessing until the end. Maybe you should give it a read and figure it out for yourself.