How to add blynk specific code in arduino code to control the arduino using blynk app

[PeteKnight]

My advice first advice would be to throw away the Uno and ESP-01 and use a NodeMCU or Wemos D1 Mini instead.

Which board should I choose for my first Blynk project?

I thought I’d write a piece about my thoughts on the best hardware to use for your IoT projects if you’re just starting-out with Blynk. I did what many people do, started-off buying an Arduino Uno and uploaded some code to make it flash an LED. After about 10 seconds of watching the LED flash I was bored, and wanted to do more (I have a short attention span ). The next task was getting the Uno connected to the internet and I chose the Ethernet Shield route. After around 6 months of m…

Then, I would be to search this forum for other projects that use this sensor, with whatever board you choose to use, and use that code as a starting point.

https://community.blynk.cc/search?q=MQ2

If you want to stick with the original plan the start by reading this:
http://help.blynk.cc/getting-started-library-auth-token-code-examples/blynk-basics/keep-your-void-loop-clean

and look at the Sketch Builder examples here:

Blynk Example Browser

Pete.