How to set the text in a header cell

In GridControl, values in header cells are set just as in any other cell.

Use an indexer on your GridControl with the row index set to 0.

//Sets Text property in the 5th column header cell.
gridControl1[0, 5].Text = "HeaderTextForColumn5";
'Sets Text property in the 5th column header cell.
GridControl1(0, 5).Text = "HeaderTextForColumn5"