In an era of ultra user-friendly website building platforms, you can easily make it from the start to the finish of the web design process without knowing any code at all. That said, there are free resources if you want to develop the skills to integrate further customization or just gain a better understanding of how web design works.
In addition to tutorials, W3Schools also provides thorough references on a variety of coding-related topics. One that might be useful if you are designing your own site or pages is the reference on cross-platform color options.
For one-off questions about code, the W3C cheatsheet can be used to easily pull up the meaning and use of a particular attribute, element, or line of code. Spot-checking your code can be a useful way to learn more about markup languages.