Need help with Fitting and using a martingale dog training collar!?

I have a martingale dog training collar for my dog, I got the right size and all, but I am not sure where it is to sit on the dogs neck and that kind of stuff so any help would be appreciated.
the martingale dog raining collar I got has the partial chain on it, so does it matter where that DRing is for the leash to go on? Oike am I pulling to the side or straig twards me if the dog is on my left?