Authentication
Send your BluMint API key as theX-Api-Key header on every call. You get one key for each environment, and each is bound to your game, so a key works only for your game and only on its own environment (Before you start).
Servers
The reference lists two servers, staging first. Build and test on staging, and switch to production once your integration works there. Each server address ends in/api, so a path shown here as /tournaments/match/submit is /api/tournaments/match/submit on the environment you call.
Callbacks
Each registration endpoint, such assetCreate, lists the callback BluMint then calls on your game server, with its request and its answers. The decision table for what each answer does is on the guide page each registration links to.