how do i make a random map changer script?

I'm not the best with scripts, for now all i can do is add music to a game and edit some parts of scripts . i have been working on a game and i need a script that will teleport players to a spawn point on one of the maps i made, then the players either all die or kill all the zombies then they get teleported back to the main lobby, while the players are in the main lobby a different map that i have already created will generate and the players will get teleported to that map, and so on and so forth. I'm not sure how to make one of these scripts so if u would please try to make a script for me i would be very greatful. Thx