What exactly do you mean by team leader? Is it the person in the team with the highest score for example? Or is it a predefined user that your script chose?
Perhaps you could choose a random member from each team?
local members = redTeam:GetPlayers()
local redLeader = members[math.random(1,#members)]
The same could go with blue
Insert Teams (Example)
After that, you should see a folder named Teams in workspace. Right-click Teams and press insert object, then insert a team instance. From there, you can customize those properties.
He gave you a good code example. Use that and customize it.