Grass FX Config editing
Not sure how much you know already so i'll go over basics in case
I hope this will be of some help as coming from someone who is also still picking things up at moment this is what I learnt to get started and have some fun with it.
Make sure you are running with shader patch and activated Grass FX in shader settings in CM
Open up the extension file for the specific track you want to work on ether found in
assettocorsa\extension\config\tracks\loaded or the tracks main installation folder
Start up Assetto in windowed mode
here is a handy guide for setting up/using the free roam camera in game if you haven't already
what to do then is open the object inspector app which is found on the right hand side tab with your other in game apps
View attachment 967786
Then by moving the camera around and using Alt + Click you can select any object around the track to view information about the object, things like the name and position in the 3D space where you clicked.
View attachment 967787
In regards to grass FX here is the guide to the edits
https://github.com/ac-custom-shaders-patch/acc-extension-config/wiki/Tracks-–-Grass-FX
As an example what I got from the "wild grass" example from the Github page, used in these screenshots.
[GRASS_FX]
GRASS_MATERIALS=grass1, grass2, grass3
OCCLUDING_MATERIALS=cordoneif
OCCLUDING_MATERIALS_ALPHA=
HEIGHT_MULT=0.5
SHAPE_SIZE = 3.5, 8
SHAPE_TIDY = 0
EDGE_MULT=1
MASK_MAIN_THRESHOLD = 0.3
TYPE_OFFSET=10
"Grass Materials" section as explained on the page, this is how you tell the effect where it will be applied
These materials is taken from object viewer, in the screenshot you can see it says "Grass 1" when I had clicked on the grass area, look how I pasted it next to "Grass_Materials" Also by clicking on anything in object viewer it copies automatically to your clipboard so you do not need to type it manually! I then did the same thing for other areas of the track and separated by comas to keep it tidy.
Hope this is any help, play about with the size and density by following the Github to get things started then go from there.