How the IGLA works please? Is it a simple lock-on, shoot and forget?

I've been firing a ton of IGLA missiles, but my hit rate is extremely low.

The way I use it is: aim → wait for lock-on → fire... and that's it.

Am I doing something wrong? Do I need to keep aiming at the aircraft after firing so the missile can continue tracking it, or does it guide itself once it's locked on?

Thanks!