The basic meaning is something like "climb" or "rise", I would say, but einsteigen and aussteigen (to "climb in" and "climb out") are used for entering and leaving cars, busses, trains, etc.
aufsteigen might be used of a balloon or of smoke from a fire -- "rise up" is better here than "climb up", I suppose. But besteigen is what you do to a mountain, i.e. you climb it ("I rose the mountain" makes no sense).
And hinabsteigen would be to climb down, e.g. into a hole. A bit of a contradiction, perhaps ("rise down"?), but it's used in German.