Why do no letters appear on the LCD screen when I type?

If you look to the left of the keyboard, you will see two tan colored switches. Currently your typewriter has the right switch set to "NORMAL". This setting allows the typewriter to be used in the manner you described, to allow for a user's personal preference. If you set the tan switch to "DISP" then the typewriter will store a number of characters on the LCD for you to review before pressing the return key. The number of characters stored varies based on the set paper margins.