How to install aftermarket subwoofer with amplifier to any BMW 2011 2019

2 x MB Quart QM200W 8 inch under seat subwoofers for BMW (2 x 100 watts RMS). Bmw F16 F26 X6 X4 Bass Speakers Under Seat subwoofers Hifi System Pair 9297898. Placement on Vehicle Under Seat. And is located in Bellshill.