Randomly spawn an object on a procedurally generated plane

I wanna know how to spawn different objects on my procedurally generated map, like trees or rocks. Here's to code I'm using.

 using ProceduralToolkit.Samples.UI;
 using UnityEngine;

 namespace ProceduralToolkit.Samples
 {
     public class LowPolyTerrainExample : ConfiguratorBase
     {
     public MeshFilter terrainMeshFilter;
     public MeshCollider terrainMeshCollider;
     public RectTransform leftPanel;
     public bool constantSeed = false;
     public LowPolyTerrainGenerator.Config config = new LowPolyTerrainGenerator.Config();

     private const int minYSize = 1;
     private const int maxYSize = 10;
     private const float minCellSize = 0.3f;
     private const float maxCellSize = 1;
     private const int minNoiseFrequency = 1;
     private const int maxNoiseFrequency = 8;

     private Mesh terrainMesh;

     private void Awake()
     {
         Generate();
         SetupSkyboxAndPalette();

         InstantiateControl<SliderControl>(leftPanel)
             .Initialize("Terrain height", minYSize, maxYSize, (int) config.terrainSize.y, value =>
             {
                 config.terrainSize.y = value;
                 Generate();
             });

         InstantiateControl<SliderControl>(leftPanel)
             .Initialize("Cell size", minCellSize, maxCellSize, config.cellSize, value =>
             {
                 config.cellSize = value;
                 Generate();
             });

         InstantiateControl<SliderControl>(leftPanel)
             .Initialize("Noise frequency", minNoiseFrequency, maxNoiseFrequency, (int) config.noiseFrequency, value =>
             {
                 config.noiseFrequency = value;
                 Generate();
             });

         InstantiateControl<ButtonControl>(leftPanel).Initialize("Generate", () => Generate());
     }

     private void Update()
     {
         UpdateSkybox();
     }

     public void Generate(bool randomizeConfig = true)
     {
         if (constantSeed)
         {
             Random.InitState(0);
         }

         if (randomizeConfig)
         {
             GeneratePalette();

             config.gradient = ColorE.Gradient(from: GetMainColorHSV(), to: GetSecondaryColorHSV());
         }

         var draft = LowPolyTerrainGenerator.TerrainDraft(config);
         draft.Move(Vector3.left*config.terrainSize.x/2 + Vector3.back*config.terrainSize.z/2);
         AssignDraftToMeshFilter(draft, terrainMeshFilter, ref terrainMesh);
         terrainMeshCollider.sharedMesh = terrainMesh;
      }

    }
 }