Instructions
Open up a theme park. Click the "Build" button. Choose the type of coaster you want to build.
Choose the "Custom" option. This will forego the ready-made coasters, and allow you to build your own track. Take a look at your budget. You will need this information when building your track.
Choose the "Railed Incline" in order to get your coaster into the air. From the desired height, you can start to slope downwards and create the track. Insert loops, corkscrews, photo towers and any other types of devices you wish to use at proper points within the track. Connect the coaster back to the other side of the platform. Press the yellow "Test" button upon completion. A test run will initiate. At the end of the run, you will receive statistics of your track. You can make adjustments if need be upon reception of those points of data.