error CS0246

Hello! An error appears on the build.
The error string - using UnityEditor;

Here’s the script:

using UnityEngine;
using System.Collections;
using UnityEditor;


[CustomEditor (typeof(VehicleSelect))][CanEditMultipleObjects]
public class VehicleSelectEditor : Editor
{
	public override void OnInspectorGUI ()
	{

		serializedObject.Update ();

		EditorGUILayout.Space ();

		GUI.color = Color.green;
		EditorGUILayout.Space ();
		EditorGUILayout.HelpBox ("
                       Vehicle Select System

", MessageType.None);
EditorGUILayout.Space ();
GUI.color = Color.white;

		EditorGUILayout.HelpBox ("List of the cars", MessageType.None);

		EditorGUILayout.PropertyField (serializedObject.FindProperty ("vehicles"),
			new GUIContent ("Vehicles", "Drag youre car prefabs"), true);

		EditorGUILayout.Space ();

		EditorGUILayout.HelpBox ("Vehicle spawn point", MessageType.None);
		EditorGUILayout.PropertyField (serializedObject.FindProperty ("point"),
			new GUIContent ("Spawn Point", "Drag spawn point transform"), true);
		EditorGUILayout.Space ();



		EditorGUILayout.HelpBox ("List of the car prices", MessageType.None);
		EditorGUILayout.PropertyField (serializedObject.FindProperty ("Lock"),
			new GUIContent ("Lock Icon", ""), true);
		EditorGUILayout.Space ();
		EditorGUILayout.PropertyField (serializedObject.FindProperty ("LevelNumText"),
			new GUIContent ("Level Unlock Text", ""), true);
		EditorGUILayout.Space ();
		EditorGUILayout.PropertyField (serializedObject.FindProperty ("carsLevels"),
			new GUIContent ("Ech Car LevelUP Need", ""), true);
		EditorGUILayout.Space ();


		EditorGUILayout.HelpBox ("Icon - Button - Shop", MessageType.None);
		EditorGUILayout.PropertyField (serializedObject.FindProperty ("Lock"),
			new GUIContent ("Lock Icon", "Drag lock icon image   "), true);
		EditorGUILayout.PropertyField (serializedObject.FindProperty ("Shop"),
			new GUIContent ("Shop Window", "Drag Shop Window image   "), true);

		EditorGUILayout.PropertyField (serializedObject.FindProperty ("Buy"),
			new GUIContent ("Buy Button", "Buy Button Object   "), true);
		EditorGUILayout.Space ();

		EditorGUILayout.PropertyField (serializedObject.FindProperty ("vehiclePriceText"),
			new GUIContent ("Vehicle Price Text", "Drag Vehicle Price Text   "), true);
		EditorGUILayout.Space ();



		EditorGUILayout.HelpBox ("Main Level Name", MessageType.None);
		EditorGUILayout.PropertyField (serializedObject.FindProperty ("levelName"),
			new GUIContent ("Level Name ", "Enter Main Scene Day Mode Name  "), true);
		EditorGUILayout.Space ();

		EditorGUILayout.HelpBox ("Loading Window", MessageType.None);
		EditorGUILayout.PropertyField (serializedObject.FindProperty ("Loading"),
			new GUIContent ("Loading Object", "Drag Loading GameObject  "), true);
		EditorGUILayout.Space ();

		EditorGUILayout.HelpBox ("Customization", MessageType.None);

		EditorGUILayout.PropertyField (serializedObject.FindProperty ("mainMenu"),
			new GUIContent ("Main Menu", "Drag RingSport Component  "), true);
		EditorGUILayout.PropertyField (serializedObject.FindProperty ("customizeMenu"),
			new GUIContent ("Customize Menu", "Drag RingSport Component  "), true);
		EditorGUILayout.PropertyField (serializedObject.FindProperty ("selectButtons"),
			new GUIContent ("Select Buttons", "Drag RingSport Component  "), true);

		serializedObject.ApplyModifiedProperties ();

	}

}

To paraphrase part of your error message

The type or namespace name ‘type/namespace’ could not be found (are you missing a using directive or an assembly reference?)

Your actual error message will tell you the line in your script that this occurred in, as well as which invalid type or namespace you tried to use. Usually this is a spelling error, and it’ll typically be highlighted in red in your IDE (e.g. MonoDevelop). Alternatively, you could be missing a using directive.

This is generally one of the simplest errors to fix, so you should be able to figure out what you did wrong just by looking at your error message, and at the line in your script that your error message mentions. Once you’ve tried this, if you still can’t figure it out, we’ll need to see the whole error message you got, as the information within it is extremely useful to anyone trying to solve the error (including yourself).