Ride left until you come to the three circles. You need to set them to connect lines in one route.
Ride up and come to the end of this branch. Then go back (just a little) and do this action once again.
Now go back to the beginning and ride the branch coming through the first circle. Ride to the end - you will set the line of second circle. Go back and up to set the line on the third and on the first circle to connect them with the route.
Ride left on the short branch, then three times on the curved branch. The right setting is on the screenshot below.
Then go back and ride the route (left for all the time). You will come to the third tower.