Luckily, Boxers typically show early in the morning so finding a decent parking spot usually isn't a problem. You will need to have the entries that you got with the judging program with you - sometimes you need to show these when you park, sometimes when you enter the building. Parking usually costs $5 - 10, even for exhibitors.
Once you get in the building (or to the ring area, if you're at an outside show), it's a good idea to find your ring right away. You'll want to arrive at the show site at the very least a half-hour before your breed begins. Depending on your dog, you can spend this half-hour ringside, or away from the crowds (some dogs get too keyed up ringside - with them it's best to find a quiet space, and go to ringside shortly before your class goes in.) If Boxers are first in the ring (which is not at all unusual), you might get a chance to save a space ringside for yourself - again, it depends on your dog. Be aware of your dog at all times - tension can be high at shows, and even the most laid-back dogs can sometimes get into a scuffle for no apparent reason. Keep your dog close to you - no 6-foot leads here - and don't let your dog be rude to other dogs. There are often other breeds around the ring, and many of them aren't so understanding of Boxer antics!
Each dog is assigned a catalog number (this will be on the entry forms you receive as well). Every show has a printed catalog which lists the information for every dog in the show - AKC registered name, registration number, birthdate, sire and dam, breeder, owner(s), owner(s) location. These can come in handy, especially if you're doing pedigree research. Catalogs can cost anywhere from $3-$15. The judges have a special catalog, that only lists the dogs' numbers.
Before judging for your class starts (preferably before your breed starts), you need to pick up your armband with your dog's catalog number on it. You get armbands from the ring steward, who is usually near the table set up just inside the ring - they typically are wearing a badge or ribbon that says "Steward" on it. Grab a couple of rubberbands, too (also by the table). The armband goes on your left arm - you must wear this in the ring so that the judge can see your number to make his placements.
Most judges line up a class by catalog order - if you're brand-new to showing and you have a 6-9 month puppy dog, you might consider sending your entry in as late as possible - this gives you a better chance of not being the very first person to be judged. Pay close attention to the handlers and classes before you, so you'll know what pattern the judge is using.
(Judging procedure is discussed under "What is a dog show" so I'll just highlight some points here.)
When the judge is going over your dog, try to keep her as still as possible and facing forward. In a puppy, this is sometimes an impossible task - and judges understand that. As long as she is moving because of puppy wiggles, and not shyness or fear, it shouldn't be a huge problem. The judge will need to be able to perform the examination, though, so don't let her go wild! Sometimes a judge will ask you to show them the bite, but often they will examine it themselves. This is *not* the time to give your dog liver! Judges do not appreciate putting their hands into a liver-filled mouth.
Be sure to smile while you're in the ring - remember, this is supposed to be fun! When you're doing the down and back (or whatever pattern the judge asks for), focus on where you're going - look at the corner of the ring you're heading for. This will help to keep the dog looking forward, and will keep you from looking at your feet. As you turn back to the judge, you can take a moment to adjust the collar and lead (make sure you've practiced this first, though, outside of the ring, because it can really throw you off if you're not smooth with it). It is perfectly acceptable to stop your puppy if she's being bouncy and start your movement again, as long as you haven't gone more than several steps. (This applies to the down and to the back.) Again, watching other handlers will help you to get these tricks down.
Also, notice the handlers that are doing a lot of winning. While many people feel politics are strong at dog shows, especially in Boxers, there is no denying that professional handlers almost always have an edge over owner-handlers, simply because handling is how they make their living. They have to be good at it - and they don't have to squeeze in practice around 40-hour a week job. A good handler will be sure that the dog is presented at his best, with minimal "fussing" from the handler. Sometimes the handler is so busy setting and re-setting and baiting, you barely notice the dog.
If your puppy places in the class, you will need to line up in the ring in order of placement - usually by the steward's table. The steward and/or the judge will mark down your number, and give you your ribbon. You may then leave the ring. Be sure to thank the judge, and congratulate the winner, even if you disagree with the placement (this is what good sportsmanship is all about!). If you take the blue ribbon or second place, you'll need to stay nearby for Winners/Reserve. Screaming, hollering, and jumping up and down is not appropriate, whether you're in the ring or ringside (a debatable exception is when your dog finishes). If you have questions for the judge about why he placed your dog the way he did, now is not the time.
Remember, a judge is only giving you his opinion on your dog on that day - if you don't like it, remember his name and don't go back to that judge. Many people keep a judges' book, where they write down the judges they showed to, what they liked and disliked, and how fair they felt the placements were. Be warned - if you find after several shows that you think every single judge needs his head examined, you may be suffering from "kennel blindness." You need to step back and take a thorough, objective look at your dog compared to the breed standard - without involving your emotions. We all think our Boxers are the best ones in the world! (And they all are )
Once judging for your breed is over, unless you took Best of Breed and will be competing in Group competition, you are free to go home. (Group competition is optional, but it is consider very poor taste to skip the Group if judge who awarded your dog BOB that day is also judging the Group. Best in Show competition is mandatory for Group winners.) When you get home, after you've taken care of your puppy, sit down for 1/2 an hour and think about how your day went, what you did right, and what you could improve. You may want to keep a journal. After that, let it go - you've got too much to do preparing for the next show!