How to add to a position when using instance.new?

I'm trying to make a function which when a player joins it creates a new part in a different position, I want them to separate by adding to the position. Here is the code I used:

`game.Players.PlayerAdded:Connect(function(newbuildingspot)

local NewBuildingSpot = Instance.new("Part")
NewBuildingSpot.Parent = game.BuildingSpotFolder
NewBuildingSpot.Size(3,5,50)
NewBuildingSpot.BrickColor = BrickColor.new("Beige")
NewBuildingSpot.Position(+0,+12,+15) `

end) Mainly concerned on the last one and wanted I hope that someone with more experience can point out my error/s.

You should use a Local Script, which only affect on player's client (only himself, like the Minecraft ender chest)

game.Players.PlayerAdded:Connect(function(player)
	local NewBuildingSpot = Instance.new("Part", player.CurrentCamera)
	NewBuildingSpot.Parent = game.BuildingSpotFolder
	NewBuildingSpot.Size(3,5,50)
	NewBuildingSpot.BrickColor = BrickColor.new("Beige")
	NewBuildingSpot.Position(math.Random(0,12), math.Random(0,15)) -- Randomize the Building Spot's Position
end)