- Place a satellite high up and just leave it there. It falls and crashes.
- Repeat, but this time give it a small push sideways. It still falls and crashes. But this time it didn't fall straight down. Because, it had some sideways speed that moved it sideways. It crashes slightly more to the side.
- Repeat, but push much harder this time. It still falls and crashes, but it crashes maybe several hundred kilometers away from the point it is hovering above. This is because you gave it a large sideways speed; while falling it still moved sideways as well.
- Now, finally, repeat, but push much, much, harder! As always, it still falls. But this time it misses Earth. It does fall towards Earth, but the sideways speed is so large, that before it lands, it has moved sideways away from Earth. It falls but misses.
When it falls but misses, it will fall past Earth. Now it is on the other side, moving away from Earth. Gravity still pulls in it, so it slows down until it stops and starts falling back towards Earth, this time from the other side. The same thing happens: it falls but misses. And everything repeats itself. This will repeat itself forever.
The path it takes in this way is an ellipse. Give it a bit more sideways speed to start with, and the ellipse becomes slightly wider. With some specific sideways speed, the elliptic path is just wide enough to be just as wide as it is long - the path is now circular (which is just a "special-case" of an ellipse). With an even larger sideways speed, the path will be wider than it is long, and we have an ellipse again, just a "fat" one instead of a "thin" one.
This is how orbits work for any celestial object, including our own satellites, moons, suns, stars and planets. If something orbits in a circular path, there is nothing special about it; it just happened to have the fitting initial sideways speed.