Excellent question! We want to first preface this by saying that bonsai is, inherently, an art form. How you decide to shape or trim your bonsai is up to you and will be informed by how you want your plant to look.
The first things you're going to need are your plant, a shallow pot (the word 'bonsai' roughly translates to English as "planted in a shallow container". Think roughly 4 inches deep), some simple succulent soil (like Bonsai Jack) and plenty of patience.
The next step is simply to plant your jade plant in the shallow pot with the succulent soil. We have a guide on planting succulents on our FAQ page with a lot of good info on that subject. Jade plants like indirect light, infrequent but deep watering and high temperatures (just don't let them freeze). They're very forgiving and you shouldn't have trouble growing them, as long as you don't over water. If you do run into trouble, feel free to ask us for help!
Then, let the plant grow. Jade plants are slow growers so this is where "plenty of patience" will come into play. As the plant grows, you may be dismayed to find that it begins to get top heavy and flop over. Don't be. This is exactly what we want. The excess leaves are still producing vital sugars that are being used to grow what we're really after, a thick trunk. Just support the tree with kebab skewers or any sort of stick like objects and keep letting it grow.
After a year in the shallow pot, it's time for your first trim. It's preferable to trim in the spring when your plant is actively growing. Bonsai is scary because you have to be very aggressive with your trimming. What you're looking for with your first trim is, essentially, to turn your plant into a twig. You'll remove most of the foliage, just be careful not to remove it all. Jade plants (and many plants in general) have an almost "contrarian personality", meaning if you trim a side of your plant down, it will fill that spot with even more foliage. Use this to your advantage by heavily trimming the areas where you want to see the most growth. At first, this is nearly everywhere so really show that bonsai who's boss!
The rest is up to you! You can experiment with trimming different parts of your plant as the years go by and, as the trunk thickens, your plant will be able to support more foliage. You can also wrap some of your plant's branches with wire. This will allow you to bend a branch where you want it. After a year or so, you can remove the wire and the branch will stay in place. You can shape your plant however you please with this method.