Then I tested the hello world sketch from the tutorial section with LiquidCrystal lcd(14, 15, 16, 17, 18, 19). Unfortunately I don’t see anything. No backlight, no letters, nothing.
Pay attention to H-8 (which isn't there yet). It will say something like: "Didn't deal with R/W (LCD pin 5) correctly."
No backlight, no letters, nothing.
On my Blue/White display you cannot see anything without the backlight so you should get the backlight working first. This has nothing to do with the Arduino other than the fact that you will probably get the power for the backlight from the Arduino pc board.
That's why I used the word "yet". I didn't mention how to deal with R/W but if you are going to add that second sentence you should qualify it with "In most cases ...".