public Form1() { InitializeComponent(); foreach (DataGridViewColumn column in dataGridView1.Columns) { column.SortMode = DataGridViewColumnSortMode.NotSortable; } Form2 form2 = new Form2(this); form2.Show(); map = new Dictionary <char, int>(); map['A'] = 0; map['B'] = 1; map['C'] = 2; map['D'] = 3; map['X'] = 4; map['E'] = 5; map['F'] = 6; map['G'] = 7; map['H'] = 8; map['Y'] = 9; map['I'] = 10; map['J'] = 11; map['K'] = 12; map['L'] = 13; map['a'] = 0; map['b'] = 1; map['c'] = 2; map['d'] = 3; map['x'] = 4; map['e'] = 5; map['f'] = 6; map['g'] = 7; map['h'] = 8; map['y'] = 9; map['i'] = 10; map['j'] = 11; map['k'] = 12; map['l'] = 13; rows = dataGridView1.Rows; rows.Add(new Object[] { "A" }); rows.Add(new Object[] { "B" }); rows.Add(new Object[] { "C" }); rows.Add(new Object[] { "D" }); rows.Add(new Object[] { "X" }); rows.Add(new Object[] { "E" }); rows.Add(new Object[] { "F" }); rows.Add(new Object[] { "G" }); rows.Add(new Object[] { "H" }); rows.Add(new Object[] { "Y" }); rows.Add(new Object[] { "I" }); rows.Add(new Object[] { "J" }); rows.Add(new Object[] { "K" }); rows.Add(new Object[] { "L" }); for (int i = 0; i < dataGridView1.RowCount; i++) { for (int j = 0; j < dataGridView1.ColumnCount; j++) { if (i == 4 || i == 9) { rows[i].Cells[j].Style.BackColor = Color.Green; } } } Courses = new List <Course>(); form2.focus(); }