Simply copy over a whole existing tier and edit its values to your liking, after that save your configuration and reload the plugin. Your new tier should appear when using /bolt list.
Just add the silent argument at the end of your command, e.g /bolt give [user][type] [amount][uses] -s. For example, the following command would silently give the user N0RSKA a tier1 lightning wand with 50 uses: /bolt give N0RSKA tier1 1 50 -s
Simply use "infinite" instead of a number when executing the command. e.g /bolt give [user][type] [amount] infinite. For example, the following command would give N0RSKA a tier1 lightning wand with infinite uses: /bolt give N0RSKA tier1 1 infinite