Lets say that you already have <asp:Table id="[TABLEID]"> on your page.
Sample how to add 1 row to table.
It would be smarter to use loop, but I leave that to you.
//Create new TableRow
TableRow row = new TableRow();
//Create 3 cells
TableCell cell1 = new TableCell();
TableCell cell2 = new TableCell();
TableCell cell3 = new TableCell();
//Create textboxes
TextBox box1 = new TextBox();
box1.ID = "box1";
TextBox box2 = new TextBox();
box1.ID = "box2";
TextBox box3 = new TextBox();
box1.ID = "box3";
//Add Textboxes to cells
cell1.Controls.Add(box1);
cell2.Controls.Add(box2);
cell3.Controls.Add(box3);
//Add created cells to table row
row.Cells.Add(cell1);
row.Cells.Add(cell2);
row.Cells.Add(cell3);
[TABLEID].Rows.Add(row);