One question on that is the ‘Serial.read’ command, does this command takes character frmo KEYBOARD or Serial to Serial communication?
It reads an incoming character from serial communication. There is nothing in that tutorial that directly applies to a keyboard. You can send serial data to your Arduino by opening Tools > Serial Monitor in the Arduino IDE, typing text in the input field, and then pressing Enter or clicking the “Send” button.
There is also nothing in the tutorial that directly applies to printing to an LCD, though the LCD library will use a similar code as is used for sending serial data.
The most important question that I have for me to benefit in the future is that I do not know how to place my questions under which category? I always thought the programmers have programming question and it should go to Programming category.
Questions about programming should be posted in the “Programming Questions” forum section.
Each forum section has a description explains its purpose. You only need to read these descriptions and then choose the forum section that best fits your question.