are you building in the right direction? in RCT1/2 it was easy to tell when you were working backwards, but in 3 it's very hard to see the difference. There should be a green arrow on the track for forwards, and red for backwards.
If you're still not sure, place a station piece and look for the 'traffic lights'. They should be on the left hand side of the track. Zoom in, and the red and green lights should be visible if you are facing forwards.
To ride your own tracks, click the ride to bring up its window, then click the camera icon to enter 'ridecam'.
Hope that helps :D