When you are at the menu about to start a race, you will have an option that says Tuning Setup. Select it and then select Race Engineer. You then have 4 options to choose from to tune. Select either Braking, Downforce, Suspension, or Gearing. Once you choose one, it will ask what the issue is with that particular part of the car. Simply select a problem, then the next screen will give you some options to fix it. (This depends on what part of the car you picked. Some will ask you to state your problem, then on the next screen could ask you to expand on the problem or go into more detail about it before it gives you the screen of recommendations to fix it). Just simply go through whatever options it gives you and once you get to the recommendations options, choose one and the achievement should pop once you exit out of it.