racing harness help!!

I have a 88 honda crx si with Tezno racing seats. I want to by a 4 point harness, but i dont know where i can secure. I was told you just put it through the holes in the seat an the harness is secured by the seat its self, i'm not sure about that. I dont understand how the harness secures you in your seat if its secured by the seat. I dont have a roll cage nor do i plan on installing one. i know you can secure them to rollbar. Anybody have any suggestions or know of any products for my care that i can secure the harness two. I've gotten two suggestions so far, one was to secure the harness to a rear upper strut bar, the other was to purchase a rear lower support bar from Arospeed which installs in the floor of the car and secure the harness to that. Somebody help me please!!

i just drilled a hole and bolted them in, the two side ones bolt into your stock seatbelt holes.

bolt the two side pieces to the place where your factory seat belt bolts in on both sides. Secure the back two straps to the floor with bolts (atleast 3/8" grade 8) with large washers. For added security weld a 1/4" plate around the area on the floor that you are bolting it to. Also seen people bolt them to the brackets for the back seat seat belts, but that doesnt look good as it goes all the way across the back seat.

i just drilled a hole and bolted them in, the two side ones bolt into your stock seatbelt holes.
Where did you drill to secure the two shoulder straps?