Rocket engines work by pushing out exhaust gases behind them at high speed. It's the same principle as the recoil on a gun.

> I’m basically asking how interstellar travel would even be possible.

Well, it would be very difficult. You would need either to wait a long time or to take a vast amount of fuel with you, bearing in mind that the more fuel you add, the heavier the rocket becomes and the more thrust is required to achieve the same acceleration.

And even if you do have a super-powerful rocket and a magical never-ending supply of fuel, you have to worry about the g forces, since presumably you want to travel to this other star safely and comfortably.

Of course, it's possible that someone will eventually discover some new physics that allows us to get around some of these problems. But without that, it is pretty hard to imagine how interstellar travel could ever become feasible (other than Voyager-style probes that get there very slowly and don't carry humans).