To be able to do that you need to pass the Snowhead temple. Kill Goht (the bull boss) then when you go back to the Goron village the Goron races will take place. Winning the race is not easy, but if you do win; the goron child will reward you with gold dust. You do not need to pass the whole temple and get the dust in one day, if you kill Goht, you play the song of time and will save the game. Next time you come to the Snowhead temple you can stand on a spot at the entrance that will ask you if you want to go straight to battle the boss. As soon as you defeat Goht again, you can go to the Goron races. Good luck! Then, go to the mountain smithees and either shoot the forge with a fire arrow or use hot spring water. They will thank you and are ready for forging. Without gold dust, you will get a razor sword which only lasts for 100 hits. If you give them golddust you will recieve the gilded sword, which is I think twice as strong as the kokiri sword, and it lasts forever. If you let them keep the remaining dust, it will be free.
Actually, I think you have to upgrade to the Razor Sword first, then infuse it with Gold Dust. I could be wrong but whenever I get the Razor Sword, they ask me to give them Gold Dust.