1. Download SupermetricsFunctions.xls or make a copy of this Google Spreadsheet.
  2. Get an authentication token from supermetrics.com/functions-login and copy it to the sheet, and it will automatically load some of your data.
  3. There are some examples on how to use the functions in the spreadsheet - by modifying it you can create all kinds of reporting solutions. Just type "=Supermetrics(" and some values for the required parameters. You can see all the parametrics listed here.

Note that when using the Excel version, you need to have macros enabled in Excel's security settings for the functions to work (after changing the settings, you may have to restart Excel).