Checked Property

Gets or sets a value indicating the state of the checkbox.

[Visual Basic]
Public Property Checked As Boolean

[C#]
public bool Checked {get; set;}

Boolean. True if the check box is in the checked state; otherwise, False. The default value is False.

When the value is True, the check box portion of the control displays a check mark.

[C#]

private void Detail_Format(object sender, System.EventArgs eArgs) 
{ 
    this.CheckBox1.Checked = true; 
}

[Visual Basic]

Private Sub Detail_Format(ByVal sender As Object, ByVal e As System.EventArgs) Handles Detail.Format

   Me.CheckBox1.Checked = True

End Sub