For a start, select a vertex and press Ctrl+G to smooth. Do the same with the next one (apart from vertexes bordering straight track), and keep on throughout the ride. This will vastly improve your track, but still not make it perfect.
Enable "show heartline" from every angle. That will (in all essence) allow you to see the path the car takes. That path better be smooth, and so should the track.
Try to get the basic shaping of elements right. Look at pictures, RCDB has plenty of them. Try to see where your differs from the original, and fix them. At the moment, anything could improve your track.
Each hill or top point should be lower than the previous one. As in, the Immelmann after the drop should be the second tallest point of the ride.
Fiddle around with supports a bit, try to get to know how to make them. WoodMagic isn't optimal for Steel coasters...
Read the in-game tips. They are quite helpful. Do it.
I hope this was of help. You've seemed to get the very basics right, and have put together a track, at least. NL may be a bit hard to use the first few times, but you'll get smoothing right eventually. Keep practising, and you'll be right up there in no time.
