i cannot get the drop at intersection plugin to show up in the plugins folder. whats wrong?

This has been much help so far. How about best practices to place plants where to start and how to get it on the created terrain.

I am very new to sketchup with just a basic understanding of the program. I run a landscape company and need to start doing more design work. I can create models with houses and decks but I am a little confused on how to create the terrain around the house so I can place plants on it. I and trying to work with the sandbox to create the ground but cannot get it to come together. Point me in the right direction with some tutorials or something.