Pretty simple. After you get some cash (most likely from racing) you can buy a new bike. You start off with the Lancer, and the first bike available to buy will be the Cyclone. It costs $2,500 to purchase and you must be Level 3. (Cyclone unlocks at Lv 3). You can get cash from doing stuff in the game like winning races (can be the same one if need be), collecting coins or by finishing events 3rd or better. To buy from the main menu, go down to 'Garage', then Bike Selection. From here you can buy a bike. The price will be next to it if you have unlocked it. Once you hit the A button to confirm purchase, the achievement will unlock.