When you get past the gate, you will see hill with a red coin. The only way to get up that hill is to hold Y (dash). Every once in a while, change the camera angle. Another way is by transportation. Go along the normal path of the level and you will eventually see a hole in the wall. Stand in that hole and do not press anything. You will be instantly warped to the second top layer of the mountain. The last way are the cannons. Just blast yourself up there, but be careful. Mario flies slightly below the target. Make sure you raise the cannon a little above your target. This will save some time.