You wouldn't be appearing because of the trespass. The trespass warning you received is just that, a warning. So long as you don't return to the store location, you won't be arrested for trespass.
Your court appearance would be because of the alleged theft charge (misdemeanor/petty theft). You would not be arrested when you appear in front of the judge, no. The notice to appear citation, if you get one, essentially takes the place of an arrest. Because it is a minor charge, the officer didn't arrest you, but you can still later receive the notice to appear on the charge.
The first appearance is your opportunity to hear the charge(s) against you and enter a plea. Generally speaking, it's in a person's best interest to plead not guilty and let the court set the case on their calendar. This gives you the opportunity to speak to a lawyer, have them obtain the evidence from the prosecutor, discuss with you the best course of action, and possibly negotiate a plea.
You can certainly simply show up and plead guilty, of course, at which time, the judge would sentence you. If this is a first offense, given that it is a minor charge, the likelihood of any jail time would be minimal. You would most likely receive probation
instead, which can include things like community service, restitution
, and/or attending an anti-theft class.