Take the new combination lock out of the packaging. Open the instructions and locate the factory-set combination. Use this combination to open your lock. You'll need to keep it open while you set the combination.
Think of a combination that you can easily remember. You should write it down and store it in a safe place.
Press the reset lever or use the reset tool that came with the lock. Turn every dial, one by one, to your desired code. If the lock came with a tool, use this to set each wheel inside the lock. Verify that all the digits are set up perfectly to ensure the code works.
Flip the reset lever back down after you've set your new combination. Don't move any of the numbers. Close the lock and make sure that it's still set to your combination.
Ensure the new combination works on your lock. Scramble all of the digits, then try out the combination.