This guide will attempt to give an overview of the technical/coding steps that are required to render a Metaplex NFT with any programming language/platform. I'll attempt to write it a programming language-agnostic manner; you'll need to fill in the particular methods of performing the steps with your coding language of choice.
For the purposes of discussion, we'll call the Solana account that holds the Metaplex NFTs the "NFT-Account."
The first thing you need to do is call the getTokenAccountsByOwner
JSON RPC method as documented here: