Hi Sir,
I want to know if there is any cost after 60days. As mentioned in the FAQ section, Renewal Period 60days are there any charges applied?
No, everything is free, as in, free beer. No costs now, no costs for future renewals.
but it should be renewed, right? and there is no cost!
Correct. You'll need to renew regularly, at least within 90 days, but preferable at about 60 days. It's best practice to automate this renewal: just set it up once and it'll keep going. All free of charge.
Almost 1.5 million certificates are issued daily, a lot of them renewals: https://letsencrypt.org/stats/ All free of charge 
Thank You for the information 
How do I get Started with the Purchase of an SSL certificate? It would be good if you guide me.
Well, "purchase" isn't the correct word I guess, but start with reading the documentation on:
Especially the "Getting Started", "How Let's Encrypt Works" pages. Also read about the "Rate Limits", as that's a common issue for many people.
Okay. Sure. Thank You for the help 