Reaching the Racetrack
As you enter the Road to Goron Village, look for a big stone rock on the north hill. That’s the one you must destroy. Keep moving west, crossing three wooden bridges as if you were heading back to Mountain Village.
After crossing the third bridge, turn right, and notice the nearby ramps. Yup, more ramps! Toss the Powder Keg up the first ramp, roll up after it, and repeat the process until you reach the big boulder.
Pick up the Powder Keg and place it directly near the boulder, then hold 
to assume a defensive posture. The Powder Keg does the trick, blasting the big boulder to bits and opening up the Goron Racetrack. Don’t worry if you don’t quite make it in time; simply return to the Goron Powder Keg Shop and pick up another Powder Keg, then try again.
Nice work! You could try your luck at the Goron Racetrack after blasting the boulder, but there’s no need to do so just yet. You’ll only need to beat the race again on a fresh set of days, so leave the racetrack for now, and return to the Goron Powder Keg Shop to tell the big Goron about your success.