How to reduce the flicker?

I am a beginner in learning c#,I want to make a simple animation. I do it in this way:paint the background ,draw a circle;repaint the background ,draw another circle..... but the screen looks so flickering.How can i reduce the flicker?Someone told me to use "Double Buffering",but I don't konw how to use it.Could you give me an example or modify my code for me ? Thanks!!! My code: using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; using System.Drawing.Drawing2D; namespace WindowsApplication7 { public class Form1 : System.Windows.Forms.Form { private System.Windows.Forms.Timer timer1; private System.ComponentModel.IContainer components; Pen pen=new Pen(Color.Red,5); int i=0; public Form1() { InitializeComponent(); } protected override void OnPaint(PaintEventArgs e1) { Graphics g=e1.Graphics; e1.Graphics.SmoothingMode=SmoothingMode.AntiAlias; Brush bgBrush=new SolidBrush(Color.Green); g.FillRectangle(bgBrush,ClientRectangle); //Pen pen=new Pen(Color.Red,5); g.DrawEllipse(pen,100,150,50,50); } protected override void Dispose( bool disposing ) { if( disposing ) { if (components != null) { components.Dispose(); } } base.Dispose( disposing ); } #region Windows private void InitializeComponent() { this.components = new System.ComponentModel.Container(); this.timer1 = new System.Windows.Forms.Timer(this.components); // // timer1 // this.timer1.Enabled = true; this.timer1.Interval = 10; this.timer1.Tick += new System.EventHandler(this.timer1_Tick); // // Form1 // this.AutoScaleBaseSize = new System.Drawing.Size(6, 14); this.ClientSize = new System.Drawing.Size(624, 341); this.Name = "Form1"; this.Text = "Form1"; } #endregion [STAThread] static void Main() { Application.Run(new Form1()); } private void timer1_Tick(object sender, System.EventArgs e) { //MessageBox.Show("SDF"); Graphics g=this.CreateGraphics(); Brush bgBrush=new SolidBrush(Color.Green); g.FillRectangle(bgBrush,ClientRectangle); g.DrawEllipse(pen,i+=5,150,50,50); String drawString = "Sample Text"; // Create font and brush. Font drawFont = new Font("Arial", 16); SolidBrush drawBrush = new SolidBrush(Color.Black); // Create point for upper-left corner of drawing. float x = 150.0F; float y = 50.0F; // Set format of string. StringFormat drawFormat = new StringFormat(); drawFormat.FormatFlags = StringFormatFlags.DirectionVertical; // Draw string to screen. g.DrawString(drawString, drawFont, drawBrush, x, y, drawFormat); if(i>this.Width)i=0; } } }