Create an account in Thingspeak.com for free, Create a channel and then generate an API Key.
You have to connect your ESP8266 RxTx to Arduino TxRx.Connect your DHT11 to Arduino digital pin.
Download the code from the link below & Compile and upload the code to Arduino.
Installing the DHT Sensor Library
The DHT sensor library provides an easy way of using any DHT sensor to read temperature and humidity with your ESP8266 or Arduino boards.
1) Click here to download the DHT sensor library. You should have a .zip folder in your Downloads.
2) Unzip the .zip folder and you should get DHT-sensor-library-master folder.
3) Rename your folder from DHT-sensor-library-master to DHT.
4) Move the DHT folder to your Arduino IDE installation libraries folder.
5) Then re-open your Arduino IDE.
Uploading your ESP8266 code
Having the ESP8266 add-on for the Arduino IDE installed (How to Install the ESP8266 Board in Arduino IDE). Go to Tools and select “Generic ESP8266 Module”.