This is intended as a very basic introduction for when you are learning to make requests using tools like Postman or RESTer. There's no need for authentication, JSON or similar here.
The below requests are available for you to make. See if you can list the cakes, query to see if a cake type exists and add your own.
To add a new cake, use a POST request:
https://www.r-adams.co.uk/apitestactivities/cake/
Within the body of the request, provide the parameter "name" with whatever value you want for your new cake.
name=VALUE
If it helps, POST requests should have a header such as "Content-Type: application/x-www-form-urlencoded"