Where can I register my dog?

Do you mean where can you go to get your dog micro-chipped? Any veterinarian can do micro-chipping. In my area it's around $20. The vet will give you all the info you need and then you register the micro-chip on a website.

If you contact the city or count animal care agency (governmental department) , they register dogs - if that's what you meant. They likely will require proof of rabies from a vet.