GUI Player Teleporter? Help!

I notice a few errors with this.
The first might not be an issue, but it looks suspicious: is the TextBox PlayerSelect or Text? If it's PlayerSelect, then the line should be this:

playerselect = script.Parent.Parent.PlayerSelect

Next, the for loop is probably not necessary, since there will only be up to one player with the name specified. You can achieve the same effect with this:

local player = game.Players:FindFirstChild(playerselect.Text)
if player then
	-- Rest of code here.
end

Finally, you're trying to set the Position of the character (a Vector3 value) to a CFrame. Since this won't work, you should do this instead:

local target = player.Character.Torso.CFrame
-- The long .Parent chain is not necessary; note that this requires a local script to work.
game.Players.LocalPlayer.Character.Torso.CFrame = target

The complete code should look like this:

playerselect = script.Parent.Parent.PlayerSelect

script.Parent.MouseButton1Down:connect(function()
	local player = game.Players:FindFirstChild(playerselect.Text)
	if player then
		local target = player.Character.Torso.CFrame
		game.Players.LocalPlayer.Character.Torso.CFrame = target
	end
end)