Hi, I realize you want to get a conversation going and that is GOOD, but these super open-ended things are not something we can really reply to in any useful way. The answer to your posted question here is "The same way as any other horse... if you don't know what that is, do some reading adn talk with your instructor..."
If you run into specific problems or have specific issues of puzzlement, like "my horse won't walk onto a sheet of plywood in trail classes, what can I do about it" or "I'm having a hard time getting my pony to stay squared properly behind in showmanship" THEN you could probably get some good conversation and advice
Google "training horse for showmanship", or something like that, and you will find a large number of very informative websites, also discussions of peoples' specific questions about it.
Once you have got started working with the horse and determined where your difficulties lie, your trainer should for darn sure be able to help you with those specific issues even without knowing about showmanship classes in particular (it's just horse-handling skills), or you could ask us or (probably better) ask forums that are actually devoted to those issues and therefore have a larger pool of good advice available.
If you will pardon my saying, you're kinda big for *Toby* already, you're not going to be doing much riding (trail) on a *shetland* now, are you?
You also will want to choose a "style" of showmanship to present yourself and pony with. Breed shows, have Shetlands stretched, usually have a braided forelock and the first of the mane braided to match. You as a handler, would present yourself in Saddleseat Jodpurs, jodpur boots, shirt and vest or shirt and saddleseat coat. You might carry a short whip. Used to be that Pony wore a halter with browband, throatlatch, and delicate chain under chin. They previously were shown with a braided forelock and the first of the mane braided to match Used to be the noseband and browband matched on halter, but styles change. So you will want to check halter styles and mane braiding out before investing.
This shows a well presented Shetland Pony, in a modern halter, not braided. You want to look as nice as it, so you don't wear Western clothing showing him. Clash of styles.
Checking out the Showmanship sites is totally recommended. You and pony have to work together as a TEAM, be smooth, obedient. Takes a bunch of time to get to that goal.
Are you showing locally or joining an Association that puts on shows for points, doing 4-H? Then you MUST read the Rules you show under and KNOW them. I see a lot of folks beat themselves with ignorance of the rules, get eliminated. They tell you which way to turn, what is expected, if handler can jump WITH pony or pony only, attire expected in each kind of class. Lots of folks CLAIM to know the rules, but the written word will beat someones memory!! Rule books are not hard to get hold of, read and KNOW what to do, how to look. Locally, lots of shows SAY they run under 4-H rules, but actually are mixing other Assoc. rules and 4-H, so you have to KNOW and stop the weirdness when they are wrong. I carry rule books WITH me to shows, so we have the information needed to protest Jump heights, courses or measurements of speed classes, allowed attire like English saddles in speed which is CORRECT here in 4-H.
You will be amazed at how much pony can learn with 15 minutes work with halter, feet placement, trotting with you, done daily. Standing posed perfectly while you groom him, he learns to STAY and be worked on both sides. Double reward grooming and training, in the same small amount of time. Much better than an hour on the weekend, when pony is totally bored with drilling his lesson into him!