private void Form1_Paint(object sender, PaintEventArgs e)
{
    Graphics g = e.Graphics;
    // draw here
}

public Form1()
{
    InitializeComponent();
    this.Width = 500;
    this.Height = 500;
}

Pen myPen = new Pen(Color.Black);          // width 1
Pen bluePen = new Pen(Color.Blue, 3);     // width 3
SolidBrush myBrush = new SolidBrush(Color.Red);
SolidBrush orange = new SolidBrush(
    Color.FromArgb(255, 255, 140, 0));  // alpha, red, green, blue

g.DrawArc(myPen, x, y, width, height,
          startAngle, sweepAngle);

private void Form1_Load(object sender, EventArgs e)
{
    Graphics formGraphics = this.CreateGraphics();
    formGraphics.FillEllipse(greenBrush, 200, 70, 100, 100);
    formGraphics.Dispose();
}

private void drawButton_Click(object sender, EventArgs e)
{
    Graphics formGraphics = this.CreateGraphics();
    formGraphics.FillEllipse(redBrush, 330, 70, 100, 100);
    formGraphics.Dispose();
}

int x = 10;
int y = 70;

private void Form1_Paint(object sender, PaintEventArgs e)
{
    e.Graphics.FillRectangle(redBrush, x, y, 50, 50);
    e.Graphics.DrawString("x = " + x, this.Font, Brushes.Black, 10, 10);
}

private void timer1_Tick(object sender, EventArgs e)   // Interval = 50
{
    x += 5;
    this.Invalidate();
}

tick 10 at 642 ms: x = 60
tick 30 at 1909 ms: x = 160
tick 50 at 3177 ms: x = 260

int L1x = 5;   // fields: outside every method,
int L1y = 5;   // so they keep their value between ticks

private void timer1_Tick(object sender, EventArgs e)
{
    label1.Left -= L1x;
    label1.Top -= L1y;
    if (label1.Left + label1.Width > ClientSize.Width || label1.Left < 0)
        L1x = -L1x;   // bounce off the left or right border
    if (label1.Top + label1.Height > ClientSize.Height || label1.Top < 0)
        L1y = -L1y;   // bounce off the top or bottom border
}

enum Position { Left, Right, Up, Down }
Position objectPosition = Position.Right;

private void Form1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.Left) objectPosition = Position.Left;
    else if (e.KeyCode == Keys.Right) objectPosition = Position.Right;
    else if (e.KeyCode == Keys.Up) objectPosition = Position.Up;
    else if (e.KeyCode == Keys.Down) objectPosition = Position.Down;
}

// in timer1_Tick
if (objectPosition == Position.Right) x += 5;
else if (objectPosition == Position.Left) x -= 5;
else if (objectPosition == Position.Up) y -= 5;
else if (objectPosition == Position.Down) y += 5;
this.Invalidate();

Bitmap picture = new Bitmap("mushroom.png");   // a field: load once

private void Form1_Paint(object sender, PaintEventArgs e)
{
    e.Graphics.DrawImage(picture, x, y, 64, 64);
}

private string[] frames = { "frames/run0.png", /* ... */ "frames/run7.png" };
private int currentFrame = 0;

private void animationTimer_Tick(object sender, EventArgs e)
{
    currentFrame = (currentFrame + 1) % frames.Length;   // 0, 1, ..., 7, 0, ...
    frameImage.Image = images[currentFrame];
}

private void tmrMain_Tick(object sender, EventArgs e)  // Interval = 10
{
    if (pnlMain.Width < targetWidth) pnlMain.Width++;
    if (pnlMain.Height < targetHeight) pnlMain.Height++;
}

private void btnAnimation2_Click(object sender, EventArgs e)
{
    pnlMain.Height = targetHeight;
    while (pnlMain.Width < targetWidth)
        pnlMain.Width++;
}

label3.Left += L3x;
label3.Top += L3y;
if (label3.Left + label3.Width > ClientSize.Width || label3.Left < 0)
{
    L3x = -L3x;
}
if (label3.Top + label3.Height > ClientSize.Height || label3.Top < 0)
{
    L3y = -L3y;
}