JFK was assassinated during a motorcade through Dealey plaza in Dallas on 22 November 1963. Despite some known tensions in Texas, and Dallas in particular, JFK opted for an open topped limo. As it turns out, this was not a good choice. Had it been raining, they would have used a bubble top and he would have been protected.
The building on the corner of Dealey Plaza, which was once the Texas School Book Depository, now houses a museum about Kennedy and his assassination. It is interesting enough, despite being laid out in a very awkward way so that we found ourselves having to go back and forth to get the order right.
The museum gives you a bit of background about Kennedy and his presidency, and goes into some detail about the assassination, setting out the story largely in line with the findings of the Warren Commission. What it didn't really do, was get into the whole conspiracy theory arguments that Lee Harvey Oswald was set up, or acting with others.
Aside from a few mentions of the grassy knoll and a bit of forensic information about bullet trajectories and so forth, there was little to enable you to reach any firm conclusion if you were trying to decide for yourself what actually happened. They did look at Oswald's potential motivation, indicating that his enthusiasm for Cuba may have led him to dislike Kennedy and his administration. I read one report that suggested that he was planning to move to Cuba which, if true, could mean that he was hoping to gain favour with Fidel Castro by the assassination.
Personally, I see no compelling reasons to doubt that it was Lee Harvey Oswald who shot JFK, or to persuade me that there was a second gunman. There are some elements that don't quite seem to add up. I am not convinced by the whole 'magic bullet' story, in which the first bullet misses entirely, the second 'magic' bullet passed through JFK and then hit Governor Connelly too, but then came out almost pristine and the third being the fatal shot to JFK's head; instead I prefer the version that has the first bullet hitting JFK, the second hitting Connelly, and the third being the fatal head shot. But who knows!
Of course Oswald was shot by Jack Ruby before there was any chance to find out his story, which has helped to fire the conspiracy theories.
What we do know, is that the assassination shocked the USA; it is said that everyone from the USA knows where they were when they heard that JFK had been shot.
Had he not died, he could well have gone on to win the 1964 election, but may have lost a lot of popularity over his determination to get the Civil Rights Act passed, and over the continuation of the Vietnam War.