How are the new seats anchored to seat pan?

Installing new seats in my p4,just wondering exactly how the new seats are anchored to the seat pan.along with my new seats,the hardware that came in a bag had on instructions.I have 8 anchors,8 bolts,and new long screws with washers.i know the bolts and anchors go with the seat frame holes on bottom,but what do they use to anchor the back of seat? My old seats back was Velcro and one screw was behind it,the new seats only seem to have room down at the bottom to anchor to the pan,and should I use the screws with a washer there? Or do I use bolts and anchors on the back?,any help would be appreciated. Thank you,fshn4lmt