public partial class FrmSideBar : Form

    {

        private Form1 mainForm = null;

        public FrmSideBar(IntPtr frmPtr)

        {

            InitializeComponent();

            this.mainForm = (Form1)Form1.FromHandle(frmPtr);

            int Y = Screen.PrimaryScreen.Bounds.Height- this.Height- ;

            int X = Screen.PrimaryScreen.Bounds.Width - this.Width;

            this.Location = new Point(X,Y);

        }

}

            Program.frmSideBar = new FrmSideBar(this.Handle);

            Program.frmSideBar.ShowDialog();

    static class Program

    {

        public static Form1 form1 = null;

        public static FrmSideBar frmSideBar = null;

}