Your flights are now (if you have a late version of the
firmware) automatically downloaded to your SD card, if
it is plugged into the memory slot in your flight computer. The flight data file
is an IGC formatted file. It is basically automatically valid.

If you want to be sure and validate it then you need to transfer it to your
computer and run vali-bra.exe in a command window (I'm assuming Windows 7).

You can find vali-bra.exe
here (right
click and save).

It's easier if you put vali-bra.exe in the same folder as the IGC file.