How do I make my Character spawn in a specific area when they join the game?

For the spawns in the arena disable the neutral spawn.

You can make a table full of spawn locations and pick randomly using math.random. Concept would look like this:

local spawns = {
    part1.Position
    part2.Position
    part3.Position
}

plr.CharacterAdded:Connect(function(char)
    char.Positon = spawns[math.random(1,#spawns)]
end)

To make it so that players spawn in a specific spot just put a spawn location. Here is a video on how to make one: https://www.youtube.com/watch?v=7yh1Qda0LXg

If you have any more questions please let me know!