How to make a msg giver script?

You could use the PlayerAdded event, and also use the if coding so that the script doesn't error;

local function Chat(plr,msg) --Heres our Chat function

if msg:lower() == "bb" then --If the Player types 'bb then
if game:FindFirstChild("Lighting") and game.Lighting:FindFirstChild("Pass/Shoot") and plr and plr:FindFirstChild("Backpack") then --This will check to see if Lighting, Pass/Shoot, The Player, and the Player's Backpack are existant
local GiveTool = game.Lighting["Pass/Shoot"]:Clone() --This will clone the object
GiveTool.Parent = plr.Backpack --This will Parent the Cloned object into the Player's Backpack
end --This ends the code for the second 'if' statement
end --This ends the code for the first 'if' statement

end --This ends the code for the 'Chat' function

game.Players.PlayerAdded:connect(function(plr) --Heres the PlayerAdded event; This will fire everytime a Player joins; The Player whom has joined will be identified as 'plr'
plr.Chatted:connect(function(msg) Chat(plr,msg) end) --This connects the Player's Chat to the 'Chat' function
end) --This ends the code for the 'PlayerAdded' event

Hope this helped!