Call the police. They'll show up, collect statements and insurance information from each of you, assess the scene/situation, created a police report, and (unless you opt to arrange it yourself) take care of towing.

If the other person is friendly, it's polite to exchange insurance information and basic contact information (like first name and contact number). But, use your discretion if they're not. The police and insurance will take care of everything, and you don't actually need to interact with the other driver in most circumstances.

Then, call your insurance company to report the crash. Usually needs to be done within 24 hours of the crash. They may or may not need you to get a copy of the police report yourself. Most of the time they can get it themselves.

When they go to process the claim, they'll contact you to make a full statement about the situation - how the crash occurred, who was headed in what direction, etc. Beyond that, your role is usually done.

They'll send someone out to where your car was towed to assess the damage, get the other person's insurance from the police report, contact their insurance, and arbitrate the matter between themselves. Depending on your coverage and the extent of the damage, that might be the end of it, they might arrange for your car to be fixed, or they might send you a check for the car's value.

If you get sued, they'll assign you a lawyer and you'll need to testify in court. Rare that it goes that far though.