In Excel:

1. Select the date column by clicking on the header in excel

2. Format menu > Cells

3. Select Date and then select the example like that is in ‘yyyy-mm-dd’, this is shown something like 2012-03-14’

4. Hit Ok and notice that the dates have all changed to the right format

5. File > Save as > Enter a file name and change the File Format to “Comma Separated Values (.csv)”