Well, if you're new to Star Wars, then you are about to start a love/hate relationship with George Lucas. And you need to know one word: Ewoks. Prepare for the Ewoks. Well, maybe there is no way to prepare for Ewoks. They are so horrible, you can't really imagine how bad. George Lucas lost his mind when he put Ewoks in the third movie. Although, as bad as they are, Ewoks are not the nadir of the Star Wars movies. That honor goes to Jar-Jar Binks. Who is probably the most racist character in film. Except for maybe Al Jolson in The Jazz Singer, which is an actual black-face minstrel show. So just gird yourself for Ewoks in the third movie, and Jar-Jar in the fourth. After that it gets a bit better, except Hayden Christensen is horrible as Darth Vader. There is no way Hayden Christensen could turn into David Prowse, or have the voice of James Earl Jones.
Anyway, the best movies are the first and second (which Lucas stupidly calls Episodes IV and V). And maybe the second one is the best of all. It should also be noted that the second one (Empire Strikes Back) had the least input from George Lucas, so that tells you something.
You should also look up the changes Lucas made to the first movie. The worst of which is when he changed when Han Solo shoots Greedo. In the original version, Han shoots first. But Lucas changed it to Greedo shooting first, and Han retaliating. Which completely changes the Han Solo character from swashbuckling space-pirate/ smuggler, to being a super good-guy, right from start of the movie. Which then completely negates his final transformation into hero at the end of the movie when he swoops in to rescue Luke from Darth Vader. When you manage to tell a story where dramatic circumstances cause an existential change in a character, that is excellent story-telling, worthy of the greatest Greek tragedies. Since Lucas didn't even realize what he had done, Lucas is a moron. He is one of the best examples of an artist who doesn't understand his own work. Also, his changes show him to be an incompetent steward of the Star Wars Canon, and ownership should be taken away from him by eminent domain or in the interest of the public good.