In ROBLOX Studio, when you play a game that you are working on, if there are any errors in your script, it will show up in the Output window. Looking at those errors will help you figure out what is wrong with your script.
Output article on ROBLOX Wiki
If I go in ROBLOX Studio and add your script as a LocalScript and run it, I will get this error in the output window:
13:42:56.240 - DamegeBall is not a valid member of Backpack
13:42:56.241 - Script 'Players.Player1.Backpack.LocalScript', Line 5
13:42:56.241 - Stack End
This tells you both the line number that the error happened on, and what the error was. In your case, you never set the Name property of the new Tool that you created, so the name is still Tool. On line 5 when you try to set the Fire's parent to game.Players.LocalPlayer.Backpack.DamegeBall, you get an error because there is no item with that name in the Backpack.