Hi & welcome! Rocky looks awesome! He doesn't have any branches yet, but will. He currently has a single stem, and his leaves are compound. If you snip off the new leaf that is forming at the tip, that will redirect the flow of auxins and send a "branch out" signal to the plant. This alone almost always leads to bifurcation of the tip.
To further guide development, increase the number of new branches and where they develop, remove the leaves where you want new branches to grow.
If you would like a more fast-growing plant on which to experiment, Coleus can teach pruning very quickly. They are easy to find in the spring with the annuals (although they are tropical shrubs and can be kept alive indefinitely in the captivity of a pot.)
These are the most basic of pruning techniques. Bonsai literature can guide you into more detail.
