Okay. So, this exercise is one of my personal favorites but I've heard my students call it everything from the wheel, to the circle of death. Yes. That's what they say.
The thing about this exercise is that it gives you an opportunity to learn so MUCH about you and your horse! The poles can either be on the ground or can be raised to small jumps at a height that's comfortable for you and your horse. You can make two of these jumps and keep the others poles. Or if you're having difficulty with your horse wandering off the track to the outside of the circle, try raising only the outsides of the poles to create a kind of funnel. (Not a NASCAR track please!)
Try this at a trot first. Pick a direction. Probably your "good" direction to start. Enter the exercise wherever you want with a good, forward pace. Try to keep your bend even and your horse balanced. This is a valuable opportunity to check where you're sitting, how you're asking your horse to bend, and how even your pace is. If you're leaning you're never going to hit those poles where you're aiming to cross them.
Now. When you've advanced to doing this exercise with small fences at a canter, the goal is to get the distances perfectly. Don't make the exercise too small. Give yourself some room. You can control your distances by choosing how tight to make the circle or not. This is a fantastic exercise to increase your steering because you and your horse will figure out where you're going after a few times around the circle and you can actually work on what you're doing between your seat and your hands. Focus on communication with your seat, balancing yourself in your stirrups and keeping a balanced half seat between fences. Really pay attention to what it feels like to make a clean turn and you'll be surprised how much better those bending lines will get.
Have fun and I can't wait to hear how you like the wheel!