I just did my very first data log this morning. So yes, you save it to your local laptop first, then along with the actual calibration you used, you send both the calibration file and the datalog file to your etuner. It is also recommended that you note the temperature, approx. humidity level, weight of yourself (and passengers), any/all mods in the car, your elevation (or zipcode), etc. - basically anything that would make the datalog more relevant and therefore the analysis/tune more accurate.
Will