Personal portfolio navbar isn't working?

So I’ve been trying for a couple days to learn about navbar and how they work because they always come out bugged for me. Even if I copy and paste the examples from the bootstrap website, navbar isn’t showing and I’m just wondering what I’m doing wrong? Is there anything online that I should be looking up specifically?

For starters you need to add jQuery and Bootstrap 4 JavaScript libraries to your Codepen settings.

Bootstrap is already added to the pen but I didn’t know I needed to add jQuery as well.

Edit: So I just switched from bootstrap 4 to bootstrap 3 and everything is showing now. I’m guessing they’re written differently? Should I be writing my code for bootstrap 4?

The syntax has changed quite a bit for the new version (4).

That is totally up to you. If you are creating projects for older browsers, then I would stick with Bootstrap 3, but Bootstrap 4 takes advantage of the newer features in CSS like flexbox. If you want latest and greatest, go with Bootstrap 4. If you want a solid framework that has been around a while and used by thousands of websites, go with Bootstrap 3. This is just my opinion.