I have very little previous experience with HTML and CSS, and doing the introductory tutorials I felt like I was learning a new language. As Long as I remembered the patterns, and had the instructions in front of me, I could replicate what the tutorial intended for me to do in each circumstance, but I felt as though I lacked the basic knowledge that would allow me to apply what I learned to anything practical. It was fun to watch the outcomes of the work and understand how HTML and CSS function yet I was limited to exactly what the tutorial was teaching me, and thinking about doing it on my own still seems daunting.
Emma, this is a totally natural reaction. Tutorials are great to give you an overview but the real learning comes from having a specific goal in mind and then having to figure out what you need to learn in order to realize your vision. Keep at it!
I also feel the same, but if you are curious about the ganging more knowledge of HTML and CSS, then you should take more advanced tutorials.