importing invoice/transacton into sage.

I see that there is an option under file>import/export which lets you import .csv file of transaction into sage.  we are using third party application to create invoices but to do the accounting we have to import the invoices into sage.  I just need to know the column format of the .csv fie which sage accepts.  eg.  customer name, date, invoice number, hst, total  etc.  in what order does that file have to be??  all the help would be appreciated.  thank you in advance