STOP! You don't unpack or open the qrad.exe file at all. First download zhlt's (Zoners Half-Life Tools) the rad file is called the "lights.rad"
NOT "qrad.exe"
Once found. Open the lights.rad file. A window will come up. Choose the option in which it allows you to choose a program to open it with. (Don't use the internet option) Then click "Notepad" And
uncheck the box which says "Always use this Program to open this type of folder."
Once in then you can edit it. Like this:
~texturename 120 120 120 1000
Whereas:
120R, 120B, 120G, 1000 Brightness of light.
Good luck.