Jayz, there are many techniques for adding branches onto trees. For your juniper, grafting is the best way, but likely beyond your grasp right now until you get more fundamentals down. Junipers will bud back somewhat, if you let it grow long shoots, then cut them back fairly hard. With evergreens you cannot cut back to where there are no needles, or the branch will die. Just cut back pretty good after the tree grows somewhat. This is not a sure method but it may work.

The best thing you can learn early on though, is how to pick good bonsai material. I suggest you search this site and others for good information on what to look for.

Chris

How small is it?? If it's a first year seedling it might not have gotten around to growing any branches yet.
zube

Wait. Let it grow. Wait longer. Promote health.