You can set the (entire) Row BackColor or ForeColor directly:
YourRow.DefaultCellStyle.ForeColor = Color.Red;
You can set a particular Cell's colors by:
YourCell.Style.ForeColor = Color.Red;
This thread on StackOverFlow contains a number of valuable examples of working with DataGridView Color styles; I suggest you start by reading this post which shows how to use the DataGridVew's RowPrePaint Event: [
^].
And, remember that you can create pre-defined Styles to use:
DataGridViewCellStyle YourRedCellStyle = new DataGridViewCellStyle();
YourRedCellStyle.ForeColor = Color.Red;
YourCell.CellStyle = YourRedCellStyle;