The bad news is that you just DO NOT change the file extension. That does nothing to change the actual file itself.

The good news is that you already have the file in a .CSV (Comma Separated Value) format. a CSV file will open with no problem in Excel, or almost any other spreadsheet program.

Just double-click the CSV file and it should open in Excel, providing that you have the default program associated with CSV as Excel (and having Excel, it already should be).