"Most people make the mistake of thinking design is what it looks like. People think it's this veneer -- that the designers are handed this box and told, 'Make it look good!' That's not what we think design is. It's not just what it looks like and feels like. Design is how it works."
If you want to learn about design, before reading books about colors, fonts, grid layouts or how to make an inner glow in Photoshop, you should start by reading something like Don Norman's "The Design of Everyday Things" to gain an appreciation for how things work, and why. Then worry about making them look good.