You can only enter the Advanced Editor once you have first made a track using the Basic Editor.
Head into 'My Cities' from the main menu to begin creating a track (Once new city is selected)
Create a basic track in the 'Basic Editor' and save and exit to be taken back to the menu, you can now select the 'Advanced Editor'.
Once the race loads place any item in the track and save and exit for the achievement to be yours.
Here's a video demonstration.