First Park In NL2

This is my first attempt at making things in NL2! I'm looking to figure out how to use terrain editing. I've already found tutorials, I just need to actually watch them. Also, the Woodie and Hyper Twister were both handbuilt, while the Standup Twister was built in Newton 2. It had some speed issues, forcing me to try to edit it in NL2 by hand and creating some pretty bad bumps. Any tips / a way to edit track in Newton 2 without messing everything else up?