2. "How do I proceed...?"

Typical RaceDAC (and RaceChrono) user is probably a track day hobbyist with either car or motorcycle.
First check out if your current mobilephone or pda is compatible with RaceChrono: www.racechrono.com/download

With 10Hz GPS receiver and RaceChrono you get very accurate lap times. Accuracy is about 0,01 seconds. More info: Comparison of lap timing systems (5Hz and 10Hz GPS receiver versus official, magnetic strip and transponder, timing).

If you do not have suitable equipment for starters, or you do not want to risk your new phone when driving on a track: Then buy a old smartphone, it probably costs 10-20 euros/ dollars or so.
Then buy a 10Hz GPS-receiver, for example Qstarz BT-Q818XT; price is around 70 dollars/ 60 euros.
And of course; buy a RaceDAC!

Then you are able to log GPS-based data and suitable sensor data available from your vehicle. And view the graphs and see where you are braking too early or too softly, applying throttle too much or too little, or short-shifting, etc.

The biggest "eyes wide open" -moment will be when you for the first time see from the data; what you REALLY are doing out there on the track. It will be a very useful point of view to you own riding/ driving, and give you a lot of hints and tips where you can improve your performance. The fact is that you can not remember almost anything from the session you just ended.
BUT! Data remembers literally everything what you did. All the laps, all the corners.

The only "negative" side is that now you finally see how much mistakes you do/ can do in one sole corner. And there is maybe a hundred corners in a session. The positive side is that then you have extra pair of eyes which sees and remembers everything and those are watching your driving all the time. And you can concentrate to the driving on the track. And then on the pits view the data and see what went ok and what not, and what things you should change, to be faster.

That is why RaceDAC is affordable. It saves your time, fuel and tyres, because you do not have to waste any laps trying to; first find your errors, and then trying to figure out by experimenting different things one by one, and at the same time try to analyze on the fly what was good idea and what was not. That is just too much variables at one time especially for a non-pro driver. From the data you can directly see what was good idea, and what did not work.

"But, as you said, I'm not pro, so I do not need all that data?"
-Step three