When you have created and published a piece of work in California, you then hold the copyright to it. This affords you some protection against having that work stolen, reproduced, used or copied by others who do not have your permission. If someone violates your copyright protection, you can then take them to court to recover damages and prevent them from using your work.
According to the Graphic Artist Guild, after someone violates your copyright, you only have three years in which to take them to court. Once you do begin the process of taking your case to court, you will have to file a complaint. This will outline what you are accusing the other party of doing, along with outlining any damages you wish to obtain and actions you want to be taken. The other party and the court will receive your complaint. The other party can then respond. This begins a phase where you may go back and forth to work out an agreement or settlement without the case ever actually going to court.
However, if you cannot settle out of court, then your case will be heard by the court. You may have a jury trial or you could choose to just have a judge preside over the case. During the trial, both sides will present evidence of their claims. At the conclusion, there will be a verdict that will either convict the other party of committing copyright infringement or release him or her from the charges. If the person has been convicted, then the judge will rule on damages to be paid and other actions to be taken to remedy the situation and compensate you for the illegal use of your work. While this information should not be taken as legal advice, it can help you understand the process and what to expect.