Level 18
While I'm not familiar with Royal Mail or it's API these are the steps to guide you on the path.
- Go to https://www.royalmail.com/business/tools-services/apis and register for an API account, once you have the API keys, take a look at their docs here https://developer.royalmail.net/api
- Look into how to use HTTP guzzle facade to make your calls
- Look into creating a service class for this API
- Leverage that service to make your calls accordingly.
If you are stuck, try looking at other API packages for similiar mail tracking or API interaction.