How to make a roller coaster 
1 you make a track of blocks in a diagonal line
2 you place rail and powered rail on the track use redstone redstone torches and a button to power the ride
3 place signs for the name of the ride and instructions (if it requires any)
4 on some rides you can make people pay tickets(which is just paper)
5 In some you can scare people or even make it a fighting jobs coaster
6 place a minecart and push button
7 enjoy the ride