This is technically off topic for this forum. So in order to successfully obtain your Let'sEncrypt certificate, there are some "steps" you need to complete first. And I am making some assumptions here so please forgive me.
Step 1 My domain is: pavanjonnavithula.com (Got it!)
Step 2 Find a hosting provider that has REALLY GOOD SUPPORT and doesn't charge outrageous prices. You might consider reading about providers/platforms that are compatible with Let'sEncrypt services. I’m not able to make a specific recommendation for a provider. You will have to make your own decisions.
You have your domain name, now you need to find a "platform" to host it so it can be seen by everyone on the "World Wide Web".
Step 3 Consider for yourself if you are ready, willing and able to create and design the website or if maybe you might prefer to use a pre-formatted website template provided by your hosting company of choice.
Step 4 Just do it. Do the research. Contact some providers and use their support forums ASK A LOT OF QUESTIONS there to decide if you think they fit your needs. READ what their clients have to say (good and bad) about their services.
When you have a website up and running with your domain name you will then be ready to come back to this forum (should you desire) and we will help with the final step you seek, obtaining an LE certificate.
Good Luck with your new adventure
Hope this Helps
Rip