Writing code for Shift Cypher in C# [on hold]

My class lab has us write a Shift Cypher and Sub Cypher methods that are called in a button click event. Below you will find the code for this problem.

Can someone help me out with the two methods in question and also calling those methods in the event handler?

enter code here

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace String_Stuff
{
    public partial class stringForm : Form
    {
      public stringForm()
      {
          InitializeComponent();
        }

        private string SwitchCase(string input)
        {
            string str1 = input;
            string output = str1.ToUpper();

            return output;

        }


       private string Reverse(string input)
        {
            string str1 = input;
            char[] inputArray = input.ToCharArray();
            Array.Reverse(inputArray);
            string output = new string(inputArray);

            return output;
      }

       private string PigLatin(string input)
       {
           // rules: words that begin with a consinant-
           //is moved to the end and "ay" is added.
           // words that begin with a vowel-
           // the sylable "ay" is added to the end of the word.
           // e.g. eagle -> eagleay, apple->appleay.
           string str1 = input;           
           string ay = "ay";
           input = inputTextBox.Text; // already a string, no need to convert
           input = input.Substring(1, input.Length - 1) + input.Substring(0, 1);
           str1 = " the word in Pig Latin is " + input + ay; // need to use Text property to display string
           string output= str1  ;
           return output;
       }                    



        private string ShiftCypher(string input, int shift)
        {
            //Each letter in the word is replaced by a letter some fixed number of positions down the alphabet.
            //For this lab, shift by 3. Example: program, shifted by 3 will become surjudp

            string output = null;
            char[] A = null;
            A = input.ToCharArray();
            int temp;
            for (int i = 0; i < input.Length; i++)
            {
                temp = (int) (A[i] + shift);
                output += (char)temp;
            }


            return output;
        }

        private string SubCypher(string input, string charsToSub)

        {
            //Each letter in the word will be replaced by a letter from the corresponding position 
            //in a substitution alphabet. For this lab use this substitution alphabet: zeroabcdfghijklmnpqstuvwxy. 
            //Example: disk would become ofqh.
            string subAlpha = "zeroabcdfghijklmnpqstuvwxy";
            string str1 = input;
            string subCypher = subAlpha;



            string output = "";
            return output;
        }



        private void transformButton_Click_1(object sender, EventArgs e)
        {
            string input = inputTextBox.Text;

            switchCaseTextBox.Text = SwitchCase(input);
            reverseTextBox.Text = Reverse(input);
            pigLatinTextBox.Text = PigLatin(input);
            shiftTextBox.Text = ShiftCypher(input,shift);
            subTextBox.Text = SubCypher(input, charsToSub);
        }
    }
}