I have a quinny freestyle 3xl (older style model). The pushchair part is attached to the frame with poppers at both sides of the seat fabric. There are then various belts that you need to fasten round the frame - at the back of the seat (these just click together), under the seat (with velcro I think) and under the feet part. Unless this has been changed in newer models it is quite easy! I can send photos of my own one if it helps.