I often read books about the universe, everyday actually, and I often try to figure out ways to explain to myself how big the universe is, in a way that both my own brain and sense can understand - it hasn't really occured yet, but I am working on it. The universe has no edge, was there ever an edge? The universe is a sphere, and centers upon the observer, thats you, if you look up on the night sky, you are the center of your observable universe. You can't see much when looking up upon the sky at night, but just because you can't see, doesn't mean it isn't there. It just isn't observable to you. One often refer to the universe as "everything there is" and there is impossible to say there is something outside of everything - hence the universe and its non-existing edge. But this isn't really a good explanation, the universe is a dense, vast mass of stuff we can study, we have learned much, but hardly anything. But one would say "to expand, there has to be something outside of the point where it hasn't reached yet". Well, it isn't really expanding into something, its just expanding. Follow that logic why don't you.
The Big Bang wasn't really an explosion has the way we think about an explosion. with mass shooting of the center of the explosion. But just as there is no edge, neither is there no center. The universe is evenly dense all over, and when talking about expanding, we don't really mean that galaxies, planets and mass are shooting out away from each other, we mean that the fabric that they exist in, is streching. If you are looking for the observable geographical point where the Big Bang started, it would be everywhere. Meaning the universe is infinitive, and yet its expanding. Meaning some infinities may be bigger than other infinities. But if there is an edge, we will never see it, and we will never know if there is. But, everything is just theories, and there is so many things we will never know for sure or understand at all. We can just assume and hope we are getting closer to an expaination, though we propably aren't.
You may remember the plum tree in my backyard, its swarming with bumblebees right now.