Knowing the fundamentals of something is different from knowing how to apply them. That works for everything: speaking a language, driving a car, cooking a dinner... What you've learned is the fundamentals but perhaps not how you actually use them.
That said, website design is another thing by itself that takes some amount of learning. Learning how to use paint and a brush doesn't mean you can sell a painting.
If you're a video person then see if you can find videos about the designing side of websites, not so much the syntax side.