Remove the combination from the safe. Many locks come with the combination attached in some way, such as a removable sticker. Make sure to put the combination in a secure place.
Start with the dial on 0 and turn the dial to the right three times, stopping on the first number during the third time around. Make sure to stop precisely on the number, and not next to it at all.
Turn the dial to the left one full turn: You will pass the first number, which will indicate one full turn. Immediately following passing that number, stop on the second number.
Turn the dial to the right, immediately stopping at the third number. This will not be a full turn around the dial, but it will instead go directly from the second number to the third number.
Pull the lever on the safe to open it.
Call a locksmith if you have forgotten or lost the combination.