As the police, court officer or judge likely explained you were ticketed for driving a car without insurance since it is illegal to do so. Even when you are only the driver and not the car owner you should be aware if the car is insured, where the insurance documents are in case you need to show them to law enforcement and if the car owner's policy will cover you when you operate the vehicle. Those are your responsibilities when borrowing a car.
That being said, in many states there are that laws allow you to transfer the ticket for driving without insurance to the car owner instead of it staying with you, the driver. If this is possible then normally you will have to give the court information on the car owner, such as their name, address, etc, and request the dismissal of your ticket so that the court can go after the car owner for the charge of being uninsured.
If you have already paid the fine it may be too late to transfer the ticket to the car owner, if this is option available in your state or the jurisdiction in which you were cited, however you may want to contact the court to find out for certain. You may also want to seek legal counsel to find out if you can go against the car owner in court and sue for the fine amount you had to pay for the uninsured vehicle.
If you are now required to obtain auto insurance, including a SR-22, due to this driving without insurance conviction, you can get a quote for affordable auto insurance here with us.