Check out
these video tutorials on trials evolution. It will explain the basics of all if not most of the editor.
Without the basic knowledge it's kind of hard to understand, so I'd suggest you look at those videos first to have better understanding how everything works.
You'll need an interval trigger, a curved data source and an object position event.
Interval trigger: interval = 1 tick
send the impulse to the object position event.
Object position event:
tie the value of the yaw/pitch/bank depending on what axis you want to the curved data source.
Select event target to the object you want to rotate
Curved Data source:
start=0
end=359(not 360, otherwise it will spend one extra tick on the startpoint.)
looping: check the box so it is enabled.
duration: how long the object takes to make the 359 degree.
Make sure you don't use objects moved by object position events as objects you can interact with on the driveline, since it won't work properly, instead you'll need to have physics joints for that purpose.