freeCodeCamp has never advertised itself as the only material you will ever need for web development. Also, throughout the curriculum, freeCodeCamp encourages the Read-Search-Ask methodology.
- Read the lesson material, and the guides/news articles available
- Search the interweb for more information, best practices, more advanced methods
- Ask on the forum, if you get stuck after the above two
You will need a lot of external resources, the further through the curriculum you go.
Hope this clarifies.
You can also use this great source to help you with issues you encounter