Arduino UNO + ESP8266 WiFi Relay by LC Technology
Serial connection requires connecting transmit TX pin to receive RX pin. Your SoftwareSerial pins ar pin 6 RX and pin 7 TX. So your wiring should be esp8266 TX to Uno pin 6 and esp8266 RX to Uno pin 7.

Connect 5 V and ground to the pins header, not to screw terminals. The IN terminals are for powering the relay coil.

Call read readRx() in the loop(). Add delay before sending "AT" in setup to let the esp8266 time to boot.