First thing you need to do when a dog or someone else's dog bites you is to get treatment or treat the dog bite.
Some dog bites can be treated at home but other dog bites you may need to see a doctor to have them treat it or if the bite is really severe you may need emergency room treatment.
After you get treated you need to contact the dogs owner and speak with them about the dog, and or contact animal control or the police to make a report if you can't find the owner of the dog.
Most likely the dog will be taken temporarily to the pound and held at the pound for awhile to be sure it doesn't have rabies and then the dog can be released back to the owner.
In some cases you may even need to sue the dogs owner for the injuries you sustained and they will most likely be held liable for any medical bills you incur for the dog bite treatment.