Wow Levelling Engineering. Buy a Blacksmith Hammer from the Blacksmith supply. First, visit any trainer in the main cities of old Azeroth - just ask a guard, and learn Apprentice Engineering.
As was mentioned you will need some materials in order. Visit your trainer and learn Artisan Engineering. Leveling engineering is quite complicated for this reason.
Engineers can create helpful items for generally all classes to be used in PvE or PvP.
Even back in vanilla, it was.
Engineering is the most unique and (imo) the most fun WoW profession but it does require a lot of gold to make the really awesome items. Leveling engineering is quite complicated for this reason. Visit your trainer and learn Artisan Engineering.