9th ques: Can you create a simple styled website & explain how it works?

Can you create a simple styled website with navigation bar like this one:

and explain how each line of CSS code mean. It means you have to understand what you write, not copy & paste the code from Internet. [I really did copy & paste this website from a tutorial on Internet. Do you know where is it? Can you search it? ok, maybe you can do, but you'd better do-it-yourself first]