I am newbie and i want to understand watching only on indicators, is Rpi 3 B+ work quite well? I mean, are green and red lights should glowing both permanently together or red light can glows permanently and green light can fades meanwhile? Also, how can i understand does raspberry 3B+ work before installing drivers for my TFT(while display is white)
The red LED is the power indicator, it should be on whenever you have your pi plugged in. The green LED is the sd card access indicator; it goes on when the pi is accessing the sd card (which is like its hard drive). When you plug the pi in, the red light should turn on and then the green light should turn on. After that, the green light will flicker and fade on and off as you use your pi. That is normal behavior.
You have not told us enough about your TFT so I cannot answer your second question. Please edit your question and add more details, such as the TFT model, what you have tried, what isn't working, and how you think it should work. Thanks!