Once you have filed your claim, a hearing date will be set for you. Then, a summons, along with a copy of your petition, will be served by the Sheriff's Department to the person being sued.
If the defendant in your case cannot be located, you should contact the court for a continuance to give you more time to find a good address for the defendant. It is your responsibility to contact the Clerk before each court date with a new address or whatever information you may have so that the person(s) can be found.
If you settle the case before the hearing date, notify the court at once so that the case can be dismissed.