How to make ESP8266 Serial to Write on UNO

I’m trying to send data from ESP8266 to my Arduino board via serial (Tx Rx), but it is not working. I have gone through the whole documentation but it was all vain. Although I’m being able to send data from arduino serial to ESP8266-01 yet vice versa is not working. Please help.

ESP8266 is 3.3 logic, while Arduino is 5V… you should use a level converter between them.

Best.

in other kind of projects the serial comunication does not need a converter, Why on thinger yes?

is there any sample where we can use to try comunications with our arduino and ESP8266-01 as a wifi shield using AT comands?

on the official sample are repporting the follow error:
/home/edu/Arduino/ESP8266AT/ESP8266AT.ino:7:35: fatal error: TinyWiFiClientESP8266.h: No such file or directory
#include <TinyWiFiClientESP8266.h>
^
compilation terminated.
exit status 1

library oficial downloaded, after searching the TinyWiFiClientESP8266.h could be founded here:

but still not working debug shows this error:
[NETWORK] Starting connection…
[NETWORK] Cannot connect!

any other chance?