What Garwood said in Post #11, but in the very least, find a book, even if for manual machining and read up on the basic fundamentals of lathe operation and machining.
You stated in your other Threads dealing with programming, that you learn better by "hands on" and not so much from reading books. Well, the myriad of mistakes you made there didn't reinforce that philosophy. All that did was to result in a copious number of Posts to deal with programming issues that should have been done and dusted in one reply had you bent a little and read the book, or at least taken the advice given without it having to be repeated a number of times.
You can get away with making programming errors when leaning and taking the precaution to test your programs in Fresh Air, but when you start to machine parts and have them come out of the chuck, you, or someone close by, may only have that one opportunity to see the mistake.
With that Diameter/Length ratio sticking out of the chuck, it's never going to work, but I find it hard to believe that 5" of the material in the chuck would pull out with a light facing cut. Its bound to chatter the moment the tool makes contact and anyone with minuscule experience should have the sense to stop at that point. Me thinks the setup isn't quite how you're describing it.
Either get someone experienced to give you some instruction, or hit the books on basic machining before you go much further.