What format is your data currently in? If you are viewing your data in a Microsoft Excel workbook (i.e. there is .xls or .xlsx after the filename) then you can choose to 'Save As', from the File menu, and then select 'CSV (Comma delimited) (*.csv)' from the dropdown for file type. Note that saving as a .csv file will only include the single sheet that is visible, so if your Excel workbook has more than one file, make sure it is also saved first as it is.
What format is your data currently in? If you are viewing your data in a Microsoft Excel workbook (i.e. there is .xls or .xlsx after the filename) then you can choose to 'Save As', from the File menu, and then select 'CSV (Comma delimited) (*.csv)' from the dropdown for file type. Note that saving as a .csv file will only include the single sheet that is visible, so if your Excel workbook has more than one file, make sure it is also saved first as it is.