The Astral Plane (or etheric plane, whatever you want to call it) is a word used to describe the plane you project to. In this plane exists every other plane that ever will exist. So, let's say that you want to go to a plane called "Berlin", if there was such a plane. You project to the plane "Berlin" (assuming you have permission to project there) because you're already projecting on the astral plane. This is called a plane shift. There are an infinite number of planes on the astral plane. The one you project to is the "normal" one, or the one everyone generally goes to. You can go to a number of them by just looking around and shifting to different planes. However, be aware that when you shift you see if you are trespassing. Also, specific planes have specific rules. On a specific plane, perhaps the "Berlin" one I mentioned earlier, you may only be able to walk instead of think of where you want to go and be there.
Going to places on the Astral Plane is will-based. You think about where you want to go, and then you will yourself there. So, if you want to walk somewhere, you walk. If you want to go a mile away, you can think "I want to go a mile in this direction" and then let it be so. You are then there. I'm not sure about flying, in some planes you can, but you can't normally.
You can also see other entities and projectors when you are there. You also can see energy on the plane. Scanning works differently while projecting. You see energy, but you sense what it does (scan) instead of needing to scan it intensively. It is more intuitive.