If you want, you can upload the same track 5 times for this achievement.
*** Spoiler - click to reveal ***(If you don't want to pollute the servers/lists or community, delete them when done)
You could also create short/simple/easy tracks or tracks with lots of point potential to help the community, but if you just want the achievement as fast as possible you can upload the same track 5 times.
Here's how:
From the main menu, go to "Track Editor" -> "New Track" -> (Any stadium)
Place any start by pressing A from default selection.
Move a bit away from the start using curves (next default selection) and straights (
once) or anything you want.
From curves press
5 times or from straights press
4 times to get to Finish "Lines".
Place any finish line.
Connect the finish line back to the starting area in green using curves, straights, or whatever you like.
Press
to validate. It will auto pilot through your track.
*Once done, click "OK", then down and "YES" to confirm upload.
*Name it whatever you'd like, press
to confirm. Click "OK" to return to editor.
*Press
again to validate. Repeat *
The achievement will actually pop when confirming the upload, before even confirming the name of the track.