Watch a couple of anime shows and go on pottermore. Or read a book.
Why do people lie?
Ruin great friendships/save their butts from going down and blaming someone else/ and the funniest one is the one where they think that if they tell the truth, they'll hurt the one they care about. But that's kind of idiotic! Because no matter how many lies they cover it up with, the truth will come out.
How do you cheer up a friend when they're feeling down?
Managing to make them laugh and keep them smiling, listening to them and of course letting them know how great they are in little ways.