With FilteringEnabled, how do you make a forcefield?

This is what I've gotten to so far.

-- in local script
local ReplicatedStorage = game:service('ReplicatedStorage')
local Event = ReplicatedStorage:FindFirstChild('RemoteEvent')
local Mouse = Player:GetMouse()

Mouse.KeyDown:connect(function(Key)
	if Key() == 'f' then
		print('pressed f!')
		Event:FireServer('message')
		wait(8)
	end
end)

-- in server script
local Player = game:GetService('Players')
local ReplicatedStorage = game:GetService('ReplicatedStorage')
local Event = ReplicatedStorage:FindFirstChild('RemoteEvent')

local shield = true

Event.OnServerEvent:connect(function(player, msg)
	if msg == 'message' then
		print('recieved message')
		shield = false
		local ff = Instance.new('ForceField')
		ff.Parent = Player.Character --problem
		wait(5)
		ff:Destroy()
		shield = true
	end	
end)

The problem about this code is that I do not know how to get the player's character so I can insert a forcefield into it.