Modern data logging systems are a goldmine of information but reading and interpreting the data can be difficult especially if you are new to the idea.
The first piece of information you need is the time loss, or delta, to either your fastest or your coaches datum lap. This will show where you are loosing (or gaining) time and the corners to focus on.
The next most important trace is actual speed followed by brake pressure and throttle trace.
With all this info you can see where and how one lap, or driver, is faster than the other and this is the ideal basic dataset.