Navigation? No, one does not "send" a balloon anywhere except downwind.
There were early reports that the first balloon had propellers. It's hard to imagine that a few props could accomplish much in the high winds of the upper atmosphere but maybe they just act as active rudders, helping to guide the thing in some way. I read that it may be possible to have some control over direction by going up and down to catch different prevailing winds. I know almost nothing about the subject, but it is interesting that we still use them at all.
Isn't one of the problems with dirigibles that they are not very useful in high winds?
Anyway, here's more than anyone probably wants to know about balloons,
https://www.bbc.com/future/article/20230210-what-it-takes-to-build-a-balloon-for-100000ft.
The latest official statement is that the three objects shot down since the first balloon were private or commercial objects and most likely benign. I saw a report that it took two missiles to shoot down the one over Lake Huron, the first missile missed. I wonder where it ended up.
One of the justifications for shooting down the ones in Alaska/Yukon was that they were flying at civilian aircraft altitudes and therefore could pose a threat. But any weather balloon passes through civilian aircraft altitudes, once on its up and then later when it falls back down.
I saw a youtube video in which Marjorie Tayler Greene speculated that the balloon could have contained nuclear weapons. It would be an odd choice for a first-strike weapon. There must be a conspiracy theory afloat by now that it could have contained a new Covid strain. I'd hate to think that I was the first to dream that up.
I hope that balloon-gate is over now. I was beginning to worry we were in a balloon gap. I did enjoy the sanctimonious outrage about being "spied" on from people who listened in on Angela Merkel phone calls.
