Look up "Importing Files" in Excel Help. You may import files into Excel in several formats. For example, on output from Excel, you may have comma delimited fields so that the contents of each cell in a spreadsheet are written to file with a comma separating each value (irrespective of the width of the cell).
| Jan | 12 | 34 |
| Feb | 54 | 98 |
If your program produces output in this format, you can the import it into Excel.