That's cool. I did the exact same thing on a 90 Celica ST and on a 91 Celica ST. Only there wasn't much of a factory wiring harness available for the fog lights.
Did you get the pushbutton switch in the dash for your setup also? I also got these from salvaged Celicas and put them in where they belong to turn the fog lights on and off. You will need to provide a constant 12VDC power source to the relay, a trigger source (such as the headlights being on, which is normal, or the parking lights being on, which is what I did, or a constant 12VDC source, so that you can just have your fog lights on whenever you want them, without regard to the headlights or the parking lights being on).
If you can interpret wiring diagrams (and I bet you can), perhaps the picture below will be of some value to you.