When taking the missile into subassemblies, grab one of the pylons depending on the aircraft you want it to use for. You just grab the it by pylon(I suggest the upper ones), save this into subassemblies, then outfit other airplanes with it. Installing it might be easier if chosen aircraft already has it's own pylons.
When firing, choose the air-to-ground mode, then choose "Kh-38", and fire when locked.
Missile has real-life speed(up to Mach 2.2), size(4 meters length), and weight,(more than 0.5 metric tons) so be careful when slapping it somewhere.
https://upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Kh-38-sketch.svg/400px-Kh-38-sketch.svg.png
The missiles come with Jundroo's Vertigo attached to them. Vertigo's controls are standard except for presence of gyroscope(AG8) and trim. There's "missile warhead" - it's just the "Boom-50" bomb inside the missile, don't fire it, please.
IRL counterpart: http://roe.ru/eng/catalog/aerospace-systems/air-to-air-missile/kh-38mle/
https://en.wikipedia.org/wiki/Kh-38