FM8 is an incredible synth but is also known to be one of the most challenging to program.
It is based on the classic DX7 synth from Yamaha. The sounds you can get from it are really quite powerful.
I am guessing you are here because you have bought my FM8 and are wondering how to install them.
Unzip the presets and copy to a location of your choice
open Native Instruments Massive
Go to File>Options>Browser>Add
add the location of the preset pack