Your page will be something of a mock-up, so there is no requirement that all your links actually go somewhere meaningful. (It would be nice if the links didn't create an error, so link to some page saying that the site is incomplete, or whatever makes sense.) On the other hand, if you wish to simulate part of a web site by creating multiple linked pages that look good together, feel free. In many cases, you'll be working off a very large and complicated commercial site, so your design will almost certainly be simpler. Best to do some bit well, than try more than you can manage.
Pay some attention to appearance. Choose colors that look nice to you. Some Google fonts can help, but can also be overused. If you use images, choose ones you have permission to use. I listed some sources at the bottom of the images notes. Do put some work into it. I will grade you down if you just don't do much.
Pick a site with some complexity, and that you're interested in. Below is a somewhat random list of sites you might choose, to show what sort of thing I have in mind. You're not limited to those. If you have a design you'd like to follow, and aren't sure what I'll think of it, just ask.
When you're ready, post your page on Sandbox, then go here and enter the URL of the page.