Curves consists of one long winding path curving most of the time. The curves are very small at first, but then get gigantic. The goal is on a platform at the end. At the edges of the path are little inclines to help let you not fall off.
There is only one goal, the blue goal. To get it, you must go along the twisting and turning path.
It is best to be patient and to go slow. It may be tempting, but it is the best way if you don't want to fly off the path. There is a shortcut. You have to jump across the curves (except the last one) to get to the goal. But going slow is much better. Better safe than sorry.
Speedrunner Strategy Edit
If you're speedrunning, just do the shortcut and zoom from curve to curve until the last one. Then, go slow but fast.