Trello's API lives at https://api.trello.com/1. Authentication goes in the query string as key and token.
Create a Power-Up at trello.com/power-ups/admin to get an API key, then generate a token from the same page. In the examples they're written {{TRELLO_KEY}} and {{TRELLO_TOKEN}}.
Full reference: https://developer.atlassian.com/cloud/trello/rest/
curl "https://api.trello.com/1/members/me/boards?fields=name,url&key={{TRELLO_KEY}}&token={{TRELLO_TOKEN}}"curl "https://api.trello.com/1/boards/{{BOARD_ID}}/lists?key={{TRELLO_KEY}}&token={{TRELLO_TOKEN}}"curl -X POST "https://api.trello.com/1/cards?idList={{LIST_ID}}&name=Created%20from%20PostTaco&key={{TRELLO_KEY}}&token={{TRELLO_TOKEN}}"