Remember how you flew a test speeder earlier? To fly your own speeder, it needs to be placed in the garage with the other vehicles.
Right-click on the driftspeeder. In the menu, select Cut. The speeder will disappear for now, but will reappear once you add it into the correct folder.
In the Explorer, scroll to find a folder named Garage.
Instead of using paste, right-click on Garage and select Paste Into. Your speeder will then reappear.
Name your driftspeeder something descriptive like The Lightning. In the Explorer, right-click on Model and select Rename. Type the new name and then finish by pressing Enter.