How to send data from mit app to arduino

Hi everyone,

I have been working a project but I have never used mit app creater. Although I am looking for something about that, I could find like this.

I want to create a text box in my app and a button. When I press the button , it must send to arduino.
Afterthat I will use data(number) to change a delay time or control LED. Something like that.

I have already tried something that it showed under the page. View attachment 133108 View attachment 133109 ...

How to send data from mit app to arduino