Legal Question in Civil Litigation in Illinois

Re: small claims court

Actually, you could do nothing, at least for a while. A court's orders only have validity if the court has jurisdiction over both the subject matter of the dispute and over the parties -- the latter known as personal jurisdiction.

If the Illinois court lacks personal jurisdiction, its orders have no effect on you. Thus, once the plaintiff seeks to enforce the judgment against you -- through procedures in Kansas, such as registering the judgment in Kansas -- you should have an opportunity to challenge the jurisdictional basis for the judgment (although I am not licensed in Kansas and I do not know its legal procedures).

Re: small claims court

You should hire an attorney to file a motion to vacate the judgment. If you had a valid and enforceable agreement to litigate only in another place, you still must affirmative plead that agreement, meaning you must respond to the summons within the time specified in it, and assert in a written document filed with the clerk of the court that Illinois is an improper venue. If you fail to do so, your assertion of improper venue can be deemed waived. The only way for the court to know of the existence of your agreement is for you to assert it in writing. You cannot expect the court to find out about the agreement on its own.