In my area, you will go to whatever the smallest, most inconsequential "courtroom" in the city is. (This was a small city/mid sized town.) It will likely be packed full of people. The judge will call through a list of everyone and generally what they are there for: speeding, shoplifting, loitering, minor vandelism, those types of things. You will be asked if you are pleading guilty or not guilty/want to talk to a prosecutor. (Again, this is how my court ran.) You want to talk to the prosecutor, even though you know you did it and you know they can prove it. You may have to sit around a while before they will talk to you either right there in the bustling courtroom or outside where they have an office/desk set up. Then, at some point the judge will start hearing the cases that have made deals which he has to hear. (Not all cases have to go in front of the judge once a deal is made, depends on the jurisdiction and what your punishment ends up being. Shoplifting sometimes comes with some probation dending on the value of what was stolen, which would normally require going in front of the judge.)
Everyone there is overpaid and wants to go home - unless there's a bleeding heart like me. Even if the lawyers and judge make a lot of money generally, they don't get paid that much for these few hours. Some lawyers (like my then-boss) can be really heartless asshats. If you have someone like me, they will ask you what happened and want to know about it and why it happened, etc. They should - hopefully - explain things well, but if they're like my boss they won't really work with you they will just tell you what deal they are offering. If money is no object, you might want an attorney. If you have little/no income you can ask the judge to see if you qualify for a court-appointed attorney. (In the US). Otherwise, this is a rare case where it probably isn't worth the cost.