Changing my seats, have a few "?"

Well as it says iv picked up a new set of bucket seats cheap ( won't be a permanent job) as I need new seats cause the original cream leather is all torn and severely worn :(
Just wondering about fitting these new seats there universal seat so what do i need to fit them? Just a set of rails off the old seats and that should do?
Never fitted seats that wernt made for the specific car so it's all new to me on making up rails and what not .!

There is two ways, cheap or experience.
Expensive way. Buy aftermarket bmw rails and mounting brackets could be anywhere from 200-300

Cheap. Get an old bmw rail, fabricat mounting brackets and weld ever thing up. 50-100e