Recently our 99 forester lost the horn before that the cruise stopped working and prior to that the air bag light came on. Could this be connected to a bad clock spring and if so how hard is it to change?

The clock spring isn't hard to swap. It does require removing the steering wheel and air bag, and most of the steering column trim pieces on the ones I've done. Your symptoms are classic clock spring failure though.

I'm a novice never done anything on airbag systems before is there any way to access a video or some kind of manual that shows a procedure to do this repair

I think it is recommended the battery be disconnected and then step on the brake pedal a few times. Never understood the stepping on the brake pedal part. 

You could try searching youtube for a video. Ericthecarguy has lots of helpful how-to videos, not sure if he's ever done a Subaru clockspring though.

Worth a look at least. Even if you can't find one specific to subaru the basics disabling the airbag are the same for every car.