I have made a voting system but I need to have it randomize the candidates of the map.

Can you elaborate a little more on randomizing the candidates? Do you mean you need to pick 3 random players for voting?

There are a number of ways you can do this. One way I can think of is to get the Player array and use the

Random.GetRandomInt(0, Players.Length -1)

3 different times. Then just grab the player from the array with the random number.