Now put the rock_01_a.cdae and rock_01_a.dae and put them in with the rest of the veggie files. Go into the folder and copy rock_01_a.dae and rock_01_a.cdae. So for example, Map 1 has rock_01_a in it and you want that in your map. So when you go into your folder you just have to replace or add the veggie files that you want in your map into the folder.
When you go into your art folder, you are going to have to replace your brushes file and you will have to make sure you have a. To do this, I am not 100% positive, but I will give you an answer of what I do know. This will create a forest file with all the instances of the brushes. Once you are in the map editor, just press vegetation editor, and then click add new forest. So make sure in your art folder, you have a brushes.cs file in there.
But, without a brushes.cs file, you cannot do anything. This all has to be done in the world editor.