Draw borders around some cells in a tablelayoutpanel

Access properties for the tableLayoutPanel and Set the CellBorderStyle to Single

You could use CellPaint event and draw the border rectangle when needed:

tableLayoutPanel1.CellPaint += tableLayoutPanel1_CellPaint;

The handler:

void tableLayoutPanel1_CellPaint(object sender, TableLayoutCellPaintEventArgs e)
{
    if (e.Column == 1 && e.Row == 0)
        e.Graphics.DrawRectangle(new Pen(Color.Blue), e.CellBounds);
}

You can draw any kind of border using ControlPaint:

if (e.Column == 1 && e.Row == 0)
{
    var rectangle = e.CellBounds;
    rectangle.Inflate(-1, -1);

    ControlPaint.DrawBorder3D(e.Graphics, rectangle, Border3DStyle.Raised, Border3DSide.All); // 3D border
    ControlPaint.DrawBorder(e.Graphics, rectangle, Color.Red, ButtonBorderStyle.Dotted); // dotted border
}