I can't get Unity to recognise Random.Range C#

I can't get Random.Range working as a function, seemingly regardless of what I do. Neither UnityEngine.Random.Range or System.Random.Range fix it either, None of my scripts are named Random.cs, I have restarted Unity multiple times (and even updated it from 4.5.5 to 4.6). Where am I going wrong?

To be specific, the error I am getting is "Parser Error: Unexpected symbol '(' in class, struct or interface member declaration"

 using UnityEngine;
 using System.Collections;
 
 public class LevelR : MonoBehaviour {
     
     int next = 0;
     public int length = int.MaxValue;
     public string[] stages;
     public const string Alphabet = "0123456789";
 
     System.Random.Range(0,1); // This doesn't work
     UnityEngine.Random.Range(0,1); // Neither does this
     Random.Range(0,1); // This is the first thing I tried
     // Use this for initialization
     void Start () {
         
     }
     
     // Update is called once per frame
     void Update () {
         
     }
     
     public string nextStage() {
         string nextstage = GenerateString (next + 1);
         next++;
         if (next == length) {
             next = 0;
         }
         return nextstage;
     }
 
     public string GenerateString(int size)
     {
         char[] chars = new char[size];
         for (int i=0; i < size; i++)
         {
             //chars[i] = Alphabet[(rand.range)(Alphabet.Length)];
         }
         return new string(chars);
     }
 
 }