how to create prev and next button

Question

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace WindowsFormsApplication42
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void pictureBox1_Click(object sender, EventArgs e)
{
pictureBox1.Image = Properties.Resources.a;
pictureBox1.Image = Properties.Resources.b;
pictureBox1.Image = Properties.Resources.c;
pictureBox1.Image = Properties.Resources.d;
pictureBox1.Image = Properties.Resources.e;
pictureBox1.Image = Properties.Resources.f;
pictureBox1.Image = Properties.Resources.g;
pictureBox1.Image = Properties.Resources.h;
pictureBox1.Image = Properties.Resources.i;
pictureBox1.Image = Properties.Resources.j;
pictureBox1.Image = Properties.Resources.k;
pictureBox1.Image = Properties.Resources.l;
pictureBox1.Image = Properties.Resources.m;
pictureBox1.Image = Properties.Resources.n;
pictureBox1.Image = Properties.Resources.o;
pictureBox1.Image = Properties.Resources.p;
pictureBox1.Image = Properties.Resources.q;
pictureBox1.Image = Properties.Resources.r;
pictureBox1.Image = Properties.Resources.s;
pictureBox1.Image = Properties.Resources.t;
pictureBox1.Image = Properties.Resources.u;
pictureBox1.Image = Properties.Resources.v;
pictureBox1.Image = Properties.Resources.w;
pictureBox1.Image = Properties.Resources.x;
pictureBox1.Image = Properties.Resources.y;
pictureBox1.Image = Properties.Resources.z;
}
private void button1_Click(object sender, EventArgs e)
{
}
private void button2_Click(object sender, EventArgs e)
{
}
}
}

here is code for displaying image one by one now i want to ad next and prev button how can i do that....