@dzungpham0703
I buy them on Aliexpress:
https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20180706102504&SearchText=HTTM
If you apply hot air it is easy to take off the white "double sided tape" and the plastic.
The send-function is used to send updates to the controller, in your case the physical-button-switch-change. Doing the send, does not control anything on the node itself.