I am using c# to color particular cells of excel file. I am using:
Application excel = new Application(); Workbook wb = excel.Workbooks.Open(destPath); Work
Cells[row, clmn] is a range so you don't need to call get_Range() and there is a enum that you can use for colors.
ws.Cells[row, clmn].Interior.Color = XlRgbColor.rgbBlack;