How To Get Data From Datagridview Row In The Text Boxes

I had added a Columns to a dataGridView Like This 　

dataGridView1.Columns.Add("mc", "Manual Columns");

The dataGridview output like this 

i had success use  following code get " label1.Text is  VusualStudio ". How can i get Manual Columns value c#? 

Many Thank !!~

string valuetest = row.Cells[0].Value.ToString();
string valuetest1 = row.Cells[1].Value.ToString();
label1.Text = valuetest + valuetest1 ;