The serial monitor does't work

Development Tools IDE 1.x
1

I am following the tutorial and the serial monitor doesn't output anything? How should I fix that?

(MOD EDIT)

Screen Shot 2019-11-04 at 22.33.04.png
Screen Shot 2019-11-04 at 22.33.04.png2332×1866 274 KB

Screen Shot 2019-11-04 at 22.33.04.png
Screen Shot 2019-11-04 at 22.33.04.png2332×1866 274 KB

2

tianran:
I am following the tutorial and the serial monitor doesn't output anything? How should I fix that?

I don't see proof that you actually uploaded the sketch. I'm used to IDE 1.8.5 where the 'title' bar above the output window shows "Done uploading".

Any chance that you forgot to upload and only compiled?