Hi Dom,
You must have version 1.0.1 correctly installed on your system before updating to 1.0.2.
If you haven't installed 1.0.1, go to the downloads page on PixInsight's website and download the installation module for 1.0.1. You have two options: full installation with local documentation (some 20 MB) or binaries only (5 MB). Then install this module.
When 1.0.1 is installed, run the 1.0.2 update. Follow the instructions. If you haven't changed the default installation directory, the program will be on:
C:\Program Files\Pleiades Astrophoto\PixInsight LE
Enter the path above (or use the Browse button) when the WinRAR self-extracting program asks for the installation destination.
In other words, the PixInsightLE32.exe file for the 1.0.2 update must replace its existing counterpart on the folder where 1.0.1 was first installed. If you prefer, you may simply copy the .exe file manually.
This should work; please let me know.
Regards,
Juan