Legal Question in Criminal Law in California

Your first step is go to your local police to file a report. The police then make a recommendation to the local prosecutor's office whether to file a complaint and which charges. The prosecutor (usually the District Attorney's office or City Attorney's office) has the authority; they decide whether to file a complaint and if so, with which charges.

You would need to hire an attorney to sue someone civilly (for money) but not to try to instigate criminal charges. The government does that.

Your message is pretty vague about what happened. We can't tell whether this person has committed any crimes without more information. The police and prosecutors won't act unless it appears that the suspect committed one or more crimes. Even then, whether to arrest and/or prosecute will be their decision and not yours. You can tell them what's going on and ask them to take action, but whether they do so will not be up to you.

You don't need a lawyer to do any of these things.

If you are being harassed you can seek a civil restraining order. The law does not require you to get a lawyer for that purpose either, but you should if at all possible.

You may also be able to sue for money damages, but you will have to prove that the defendant's actions constitute a tort or some other legal wrong which entitles you to relief. Here again you would be much better off with a lawyer but are not required to have one.

Good luck.