The Enjin Cloud is the main backend service of the Enjin Platform that connects your game to the Ethereum Net. The Cloud acts as a hub, gathering requests from clients and game servers, interacting with the smart contracts on Ethereum, and returning data back to your game. It also manages the link between your users game account (e.g., SteamID, Xbox Live ID, etc.), and their blockchain identity (i.e., currently linked wallet address).
The main way to interface with our service is to use GraphQL, either via API or interactively using a console like GraphiQL. If you are unfamiliar with GraphQL, check out this introduction to get started using the language.
Testnet is a development version of the mainnet, where you can easily obtain fake Ethereum and Enjin Coin to test your items in a safe, simulated environment without using real cryptocurrency.
Mainnet is the real deal. You are using real Ethereum and Enjin Coin (ENJ). Therefore, transactions cost real cryptocurrency. You should be very comfortable with your implementation on testnet before doing anything substantial on mainnet.
On the right side, there should be a documentation panel to expand and browse for all the requests and parameters you can use. See here for documentation on Queries and Mutations. Queries are requests for information from the server, where Mutations are requests that modify server side data.
On the (top) left panel, you would enter in your request to be made to the Enjin Cloud. Press the “Play” button at the top to submit that request, and you will receive a response on the right panel, sometimes a notification will appear in your dev wallet to sign a transaction depending on the request made.