i want to change the button color wheni click on it

public Form1()
{
     InitializeComponent();
     button1.Click += new EventHandler(allButtons_Click);
     button2.Click += new EventHandler(allButtons_Click);
     button3.Click += new EventHandler(allButtons_Click);
     // do this for all your buttons
}

void allButtons_Click(object sender, EventArgs e)
{
     Button senderBtn = sender as Button;
     senderBtn.ForeColor = Color.Red; // set the fore color of the button
     senderBtn.BackColor = Color.Orange; // set the back color of the button
}

protected void Button1_Click(object sender, EventArgs e)
{
    if(Button.BackColor != Color.Red)
        Button1.BackColor = Color.Red;
    else
        Button1.BackColor = Color.Blue;
}