This question is an exact duplicate of:
I have created a dapp which has a front end as well as a backend server. The role of back end server is to listen to events triggered by the smart contract and execute related piece of code. So far I have tested the functionality on local Ganache only which is working fine. Now I want to deploy my entire dapp to Rinkeby Testnet. I am able to deploy the smart contract via Remix to Rinkeby but cannot figure out how to connect my backend server to Rinkeby Testnet.