how to add a datarow in to a datagridview

Well, not sure what you want to do, I would need to see some of your code for that.
But the easiest way to do this (not using any binding and such):

DataGridViewRow row = new DataGridViewRow();
row.CreateCells(dgv); // dgv is your DataGridView.
// Add values to the Cells.			
// Make sure these columns actually exist!
row.Cells["column1"].Value = dr["someColumn1"]; // dr is your DataRow.
row.Cells["column2"].Value = dr["someColumn2"];
// Add the row to the DataGridView.
dgv.Rows.Add(row);

The problem with this solution is that if your DataRow changes this code might break.
So if the DataRow comes from a database and the database is altered you need to alter this piece of code. But that is what happens if you do not use binding I guess.
If you do use binding I am not sure I see the problem, since the DataGridView should update automatically :)