On the left side of the interactive you see a region composed of a matrix of dots. This is where you will build your roller coaster. Click one of the CONVEX, CONCAVE, LOOP, or STRAIGHT buttons in the Construction Tools area below the dots to add a section of track. Once you have chosen the type of section you want to add, point your mouse to the dot on which you want to begin. Click to begin the track section and then drag out the desired length of track. Start your next track section where the last one left off, or your rollercoaster car will plunge to its doom. DELETE allows you to remove a section if you want to make a change. Clicking CLEAR ALL in the Environment section of the interactive on the right lets you begin with a clear slate.