To get started really quick, follow these steps:

1. Get a free API key: https://spoonacular.com/food-api/console
2. Learn how to use that API key in requests: https://spoonacular.com/food-api/docs#Authentication
3. Make your first request, e.g. by searching for pasta recipes: https://api.spoonacular.com/recipes/complexSearch?query=pasta&apiKey=YOUR-KEY

Check out the entire API and docs at Spoonacular Recipe, Food, and Nutrition API