How make a "for" loop that repeats its task every 0.1 seconds?

Hey. It's pretty easy. You want a For Loop, that loops around a table every 0,1 Seconds, right? You could just do this:

while wait(0.1) do -- executes every 0.1 seconds
    for i, v in pairs(game:GetChildren()) do -- add your for loop here
        -- your code here that should execute every 0.1 seconds for i and v.
    end -- for loop end
end -- while end

Example: Teleportation:

while wait(0.1) do
    for i, v in pairs(game.Players:GetChildren()) do -- example for loop, loops through players
        v.Character.PrimaryPart.Position = Vector3.new(0, 64, 0) -- example code line
    end
end

while wait(0.1) do
    -- your code here
end

Easy and simple loop. You can learn more about loops here: https://developer.roblox.com/en-us/articles/Loops